Merriam-Webster Logo
  • Dictionary
  • Thesaurus
  • Scrabble
  • Spanish Central
  • Learner's Dictionary


noun in·sect \ˈin-ˌsekt\

Simple Definition of insect

  • : a small animal that has six legs and a body formed of three parts and that may have wings

  • : an animal (such as a spider) that is similar to an insect

Source: Merriam-Webster's Learner's Dictionary

Full Definition of insect

  1. 1 a :  any of numerous small invertebrate animals (as spiders or centipedes) that are more or less obviously segmented —not used technically b :  any of a class (Insecta) of arthropods (as bugs or bees) with well-defined head, thorax, and abdomen, only three pairs of legs, and typically one or two pairs of wings

  2. 2 :  a trivial or contemptible person

insect adjective

Examples of insect in a sentence

  1. a swarm of flying insects

  2. <the magazine's editor in chief was notorious for treating staffers as insects, often not even bothering to learn their names>

Illustration of insect

Origin of insect

Latin insectum, from neuter of insectus, past participle of insecare to cut into, from in- + secare to cut — more at saw

First Known Use: 1601

INSECT Defined for Kids


noun in·sect \ˈin-ˌsekt\

Definition of insect for Students

  1. 1 :  any of a group of small and often winged animals that are arthropods having six jointed legs and a body formed of a head, thorax, and abdomen <Flies, bees, and lice are true insects.>

  2. 2 :  an animal (as a spider or a centipede) similar to the true insects Hint: This meaning is not scientifically accurate but may be encountered in common everyday use.

History for insect

The distinct parts into which insects’ bodies are divided—head, thorax, and abdomen—inspired the Greek name used for them by the philosopher Aristotle: entomon, the “notched” or “segmented” animal. (Entomon is a noun derived from the verb entemnein, “to cut up” or “to cut into.”) The Romans used insectum, a literal translation of Greek entomon, as their name for the creatures, and this Latin word has provided us with the ordinary English word for insects.

Medical Dictionary


noun in·sect \ˈin-ˌsekt\

Medical Definition of insect

  1. :  any arthropod of the class Insecta

insect adjective

Seen and Heard

What made you want to look up insect? Please tell us where you read or heard it (including the quote, if possible).


to expose to danger or risk

Get Word of the Day daily email!


Take a 3-minute break and test your skills!

Name That Thing

Test your visual vocabulary with our 10-question challenge!


Test Your Knowledge - and learn some interesting things along the way.