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general::
1. Test the fit or look of a garment by putting it on, as in Do you want to try on this dress? This expression is Also put as try on for size, which is sometimes used figuratively, as in The teacher wanted to try the new method on for size before agreeing to use it. [Late 1600s] 2. Test the effectiveness or acceptability of something, as in The actors decided to try on the new play out of town. [Late 1800s] Also see TRY OUT.
American Heritage Idioms