A Guide to Coronavirus-Related Words

Deciphering the terminology you're likely to hear

COVID-19 is “a mild to severe respiratory illness that is caused by a coronavirus,” one that is characterized especially by fever, cough, and shortness of breath and may progress to pneumonia and respiratory failure. The name is an odd sort of acronym, insofar as it is formed from portions of two distinct words (COronaVIrus & Disease) and the latter portion of a date (the 19 from 2019). COVID-19 was first identified in Wuhan, China in December 2019.


Social distance has been in use since the early 19th century, initially with the meaning of “the degree of acceptance or rejection of social interaction between individuals and especially those belonging to different social groups (such as those based on race, ethnicity, class, or gender).”

Here indeed they possess an advantage which they have not with respect to men: they are less separated by social distance.
Christian Observer (Boston, MA), May 1824 

In modern use the term is more often encountered with the meaning of “the avoidance of close contact with other people during the outbreak of a contagious disease in order to minimize exposure and reduce the transmission of infection.” The practice of maintaining a greater than usual physical distance from other people is referred to as social distancing, in use since 2003; the verb is socially distance.


Fomite (which rhymes with ‘toe blight’) is “an object (such as a dish or a doorknob) that may be contaminated with infectious organisms and serve in their transmission.” While this word is infrequently encountered, there has been considerable talk of late about possible surfaces and objects which might harbor infectious substances, and it may well be useful to have this specific word at hand.

 Ten fomites (doorknobs and toilet seats) were sampled during July 21-22 before any cleaning took place by facilities management personnel.
—Sonia Fankem, et al, Journal of Environmental Health, Apr. 2014


An outbreak is “a sudden rise in the incidence of a disease”; an epidemic is “an outbreak of disease that spreads quickly and affects many individuals at the same time”; a pandemic is “an outbreak of a disease that occurs over a wide geographic area and affects an exceptionally high proportion of the population.” An outbreak may become an epidemic if it spreads enough, as an epidemic may likewise become a pandemic.

The difference between an epidemic and a pandemic is a matter of degree, and not all the dates listed by Hoyle and Wickramasinghe can be said to be those of pandemics.
— David Lyons and Gillian Murphy, Nature, 1 Mar. 1990


Community spread is “the spread of a contagious disease within a community." It also has the specific meaning of “the spread of a contagious disease to individuals in a particular geographic location who have no known contact with other infected individuals or who have not recently traveled to an area where the disease has any documented cases.”

Prevention of community spread (and reintroduction of undiagnosed infectious TB patients into correctional facilities) requires the rapid investigation of contacts in the facility.
—Centers for Disease Control and Prevention, Morbidity and Mortality Weekly Report, 5 Feb. 1999

Contact tracing is “the practice of identifying and monitoring individuals who may have had contact with an infectious person as a means of controlling the spread of a communicable disease.”

State laws require that all cases treated by private physicians be reported to the public health departement. Yet, some doctors feel this would be violating their professional code of ethics, for if turning over to health authorities the patient is interviewed and required to give names of all his own sex contacts, as well as names of friends he suspects mght be infected. This is known as “contact tracing” and all information is kept in strictest confidence.
—Norma Lee Browning, Chicago Daily Tribune, 19 June 1960


Martial law is “the law administered by military forces that is invoked by a government in an emergency when the civilian law enforcement agencies are unable to maintain public order and safety.” We occasionally see the term misspelled as marshal law, probably due to the fact that marshal has a number of meanings dealing with the military (“a general officer of the highest military rank”) and the enforcement of laws (“an officer having charge of prisoners”).

The martial portion of martial law comes from the Latin word martalis, meaning “of Mars” (referring to the Roman god of war).


To self-quarantine is “to refrain from any contact with other individuals for a period of time (such as two weeks) during the outbreak of a contagious disease usually by remaining in one's home and limiting contact with family members.” The verb is fairly recent, showing evidence of use only within the past 20 years or so. The noun has been in occasional use prior to this in the 20th century.

Dr. Banks said further that the Federal authority invested in him in the matter of quarantine had not yet been exerted to its fullest, but that if persons continued to disregard his advice about self-quarantine, he would bring into service all of the power of compulsion at his command.
The New York Times, 10 Aug. 1916 (p. 1)

Quarantine is currently most often found with the meaning of “a restraint upon the activities or communication of persons or the transport of goods designed to prevent the spread of disease or pests.” The word has a number of other meanings, both archaic and current, many of which have to do with a period of 40 days (it may be traced back to the Latin word quadraginta, meaning “forty”), including a 40 day period during which a widow was permitted by law to remain in her deceased husband's principal home without having to pay rent to his heirs, a period of 40 days set aside for penance or fasting (in early Christian church use), or a general period of 40 days set aside for a variety of uses.

One grand inconvenience attended on this army of Pilgrimes: For when their quarantine, or fourty dayes service, was expited, (the term the Pope set them to merit Paradise in) they would not stay one whit longer.
— Thomas Fuller, The historie of the holy warre, 1647


An index case is “the first documented case of an infectious disease or genetically transmitted condition or mutation in a population, region, or family.” It may also, however, refer to an individual who has a disease, condition, or mutation that is the first one identified in a population. This second sense is synonymous with index patient. A related term is patient zero, “a person identified as the first to become infected with an illness or disease in an outbreak.” Patient zero is especially used to refer to a person documented as being the first known case of a communicable disease in a particular population or region.


A super-spreader (also written as superspreader) is “an individual who is highly contagious and capable of transmitting a communicable disease to an unusually large number of uninfected individuals.” The term for the spread of disease by super-spreaders is super-spreading.

In the Maine case, however, neither AIDS nor poverty was thought to be a factor. Dr. Ban Mishu of Vanderbilt University, who investigated the outbreak, said it began in 1989 with one "super spreader," a man who was unknowingly infected with the bacteria in his lungs and throat.
The Evening Sun (Baltimore, MD), 14 Oct. 1992

According to the news reporters, the research concluded: "Super-spreading is thus partly due to super-spreaders, but modest gains are expected from targeting super-spreaders.”
Zika & Mosquito Week, 17 Sept. 2019


Isolation ultimately derives from the Latin word insula, meaning “island.” The word’s path from Latin to English begins with the Italian derivative of insula, isolato (“isolated”), that became the French word isolé, and then moved into English. Early uses of the term in English were spelled in the French manner with a conventional English modifier ending d as isolé’d before it settled as the spelling isolated.

The literal etymological meaning of the word isolated is islanded. (The first hospitals built in Italy to protect the general population from the sick in the 14th century were located on an island.) Given its Classical roots, isolated is a relatively new word in English, only dating to the late 1700s. A verb was subsequently coined to correspond to this adjective, which is how we got isolate in English through the process of back-formation.

We date self-isolation to 1834 and a passage from The Metropolitan Magazine. In contrast to the use of the term in the context of today’s health crisis, this first known use of the term seems to make reference to being unaware of the events of the world around us:

Few, indeed, are they whose relations with actual life are compatible with a complete self-isolation from the interests and the passions fluctuating around them, and who can so effectually detach themselves from the tumultuous current of events which every day swells in its rapid course to the silent gulf of the past time.


Contagious and infectious often cause confusion, as the words overlap in significant ways, yet also have meanings which are in some ways distinct. Contagious is “transmissible by direct or indirect contact with an infected person,” and infectious is “producing or capable of producing infection” and “containing pathogenic agents which may be transmitted.” Both infectious and contagious diseases are caused by bacteria and viruses; they differ in that contagious diseases may be spread by direct or indirect contact.

An ailment such as food poisoning is infectious, it is capable of producing infection, but it is not contagious. The coronavirus, on the other hand, is both contagious and _infectious. Anything that is contagious is automatically also infectious, but the reverse is not true. Both words are frequently used in a figurative manner.

Grace’s simple, light-hearted gayety was infectious, and Warren found the grave dignity of the successful graduate rapidly disappearing.
— A Lady, Juno Clifford, 1856

She talked, sang, and recited—she exerted all the wit and vivacity of which she was mistress—she employed powers of humour which she herself had scarcely been conscious of possessing. Her gaiety soon became contagious.
— Mary Brunton, Self-Control, 1811


Virus has been used to describe something unwelcome for hundreds of years before it became a term for ‘the reason your computer is doing that funny thing that really isn’t funny at all.’ The word comes from classical Latin in which it referred a number of things which might make one wish to wash their hands (venom, pus, and poisonous emanations). The biological sense we all know and fear today (“any of a large group of submicroscopic infectious agents that are usually regarded as nonliving extremely complex molecules, that typically contain a protein coat surrounding an RNA or DNA core of genetic material but no semipermeable membrane, that are capable of growth and multiplication only in living cells, and that cause various important diseases in humans, animals, and plants”) began being used around the beginning of the 20th century. Prior to this virus had such meanings as “venom emitted by a poisonous animal,” and “a morbid corrupting quality in intellectual or moral conditions.”

I shall therefore, in the following remarks on this abominable libel, and in extracting and expelling the virus of it, substitute the word Protestant and Romanist for the words Colonist and Native.
— Patrick Duigenan, A fair representation of the present political state of Ireland, 1800