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One might expect a science-y word like collimate to have a straightforward etymology, but that's not the case. Collimate comes from Latin collimāre, a misreading of the Latin word collineāre, meaning "to direct in a straight line." The erroneous collimāre appeared in some editions of the works of ancient Roman statesman Cicero and scholar Aulus Gellius. The error was propagated by later writers—most notably by astronomers, such as Johannes Kepler, who wrote in Latin. And so it was the spelling collimate, rather than collineate, that passed into English in the 19th century as a verb meaning "to make (something, such as light rays) parallel."
Examples of collimate in a Sentence
Anthony Wood, Space.com, 15 Nov. 2025
Optical lasers are devices that emit parallel, or collimated, beams of light.
—Thomas Linker, The Conversation, 15 Oct. 2025
But black holes produce their own radiation, especially high-energy X-rays and gamma-rays, which shoot out from the star in the form of tightly collimated...
—Newsweek, 14 Mar. 2018
Cite this Entry
“Collimate.” Merriam-Webster.com Dictionary, Merriam-Webster, https://www.merriam-webster.com/dictionary/collimate. Accessed 16 Jun. 2026.
Copy CitationKids Definition
collimate
verb
Medical Definition
collimate
transitive verb
