dynamo

noun

dy·​na·​mo ˈdī-nə-ˌmō 

plural dynamos

1

: generator sense 1b

2

: a forceful energetic individual

Did you know?

The dynamo was introduced in 1867 to produce electricity for commercial use. Like all later generators, the original dynamos changed mechanical energy (produced by steam, which was itself produced by burning coal) into electricity. The word is less used today than it once was, since it's often applied only to generators that produced direct electric current (DC) rather than alternating current (AC), which is now the standard. A human dynamo is a person who seems to have unlimited energy.

Synonyms

• fireball
• live wire
• pistol

Examples of dynamo in a Sentence

a dynamo who barely needs to sleep, or so it seems

Recent Examples on the Web

The 2025 Tony Awards toasted a Broadway season teeming with delights—and lucky for us, no less a dynamo than Cynthia Erivo was on hand to host. —Vogue, 9 June 2025

The Ward-Continental-Twinkie baking dynamo had plenty of local competition only blocks away. —Jacques Kelly, Baltimore Sun, 7 June 2025

For example, the swirling dynamo of molten iron and nickel inside Earth generates our planet's field. —Paul Sutter, Space.com, 5 June 2025

Their starting assumption was that the early Moon had a dynamo that generated a weak magnetic field 50 times weaker than Earth's. —Jennifer Ouellette, ArsTechnica, 23 May 2025

Word History

Etymology

short for dynamo-electric machine, translation of German dynamo-elektrische Maschine; dynamo-elektrisch, probably by inversion of elektrodynamisch electrodynamic

Note: According to the Oxford English Dictionary (first edition, 1897), "The full name dynamo-electric machine was given by [Werner] Siemens in 1867, to distinguish his invention from the magneto-electric machines previously used, in which the electric current was generated by means of a permanent magnet." This statement appears to be based on a citation from The Times (December 5, 1882), according to which, "Professor Thompson [not further identified] said that the name 'dynamo-electric machine' was first applied by Dr. Werner Siemens in a communication made in January, 1867, to the Berlin Academy." The communication in question was "Ueber die Umwandlung von Arbeitskraft in elektrischen Strom ohne Anwendung permanenter Magnete," published in Annalen der Physik und Chemie, Band 130 (1867), pp. 332-35. The article does in fact describe a generator with rotating coils, but nowhere does Siemens use the word dynamo-elektrisch or the phrase dynamo-elektrische Maschine; the closest he comes is magnetelektrisch for the opposing term. The first appearance of dynamo-elektrisch must date some time after this.

First Known Use

1882, in the meaning defined at sense 1

Rhymes for dynamo

• afterglow
• akimbo
• albino
• aliquot
• allegro
• amigo
• apropos
• audio
• bungalow
• calico
• calypso
• cameo

Kids Definition

dynamo

noun

dy·​na·​mo ˈdī-nə-ˌmō 

plural dynamos

1

: generator sense a

2

: a forceful energetic person