turnkey I. \ˈ ̷ ̷ˌ ̷ ̷\noun (-s) Etymology:turn (I) + key : one who has charge of the keys of a prison : jailer, warder II. \¦ ̷ ̷ ˌ ̷ ̷ \adjective : supplied or installed complete and ready to operate < a turnkey nuclear plant > < a turnkey computer system > also : of or relating to a turnkey installation < a turnkey contract > < turnkey vendors >