Vigorously pursuing an activity, especially a fight, but also sex or some other activity. For example, Whenever they play bridge they really go at it (fight), or The new job keeps Tom at it day and night (works hard), or In the spring the dogs are always at it (sex). Shakespeare used this seemingly modern idiom for “fighting” in Troilus and Cressida (5:3): “They are at it, hark!” [Late 1500s]
The American Heritage® Idioms Dictionary Copyright © 2002, 2001, 1995 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company.
How to use at it in a sentence
I'm too voluminous—I'm a boiler-over, not a simmering stick-at-it.Tono Bungay | H. G. Wells
They will not, however, have the more methodical stick-at-it quality of those whose fingers are found firm and stiff.Palmistry for All | Cheiro
He likes to talk of empires and dynasties falling, and thousands of years gone by, and Good-God-look-at-it-all-now sort of thing.The Secrets of a Kuttite | Edward O. Mousley
There's so many fact'ries nowadays that Keep-at-it is the only sewin'-woman that makes a livin'.Honey-Sweet | Edna Turpin