- The definition of accustom means to become familiar with or used to something.
An example of accustom would be moving to a rainy climate and adapting over time to the weather.
accustom definition by Webster's New World
Origin: Middle English accustomen ; from Old French acostumer ; from a-, to plush costume: see custom
accustom definition by American Heritage Dictionary
transitive verb ac·cus·tomed, ac·cus·tom·ing, ac·cus·toms
Origin: Middle English accustomen, from Old French acostumer : a-, to (from Latin ad-; see ad-) + costume, custom; see custom.