(process or manner of functioning or operating; "the power of its engine determines its operation"; "the plane's operation in high winds"; "they compared the cooking performance of each oven"; "the jet's performance conformed to high standards")
(perform as expected when applied; "The washing machine won't go unless it's plugged in"; "Does this old car still run well?"; "This old radio doesn't work anymore")
(serve a purpose, role, or function; "The tree stump serves as a table"; "The female students served as a control group"; "This table would serve very well"; "His freedom served him well"; "The table functions as a desk")
(perform duties attached to a particular office or place or function; "His wife officiated as his private secretary")
(performing or able to perform its regular function; "a functioning flashlight")