tag

[count] : a small piece of cloth, paper, metal, etc., that is attached to something and that has information written on it — see also dog tag, name tag, price tag

[count] : a name or phrase that is used to describe someone or something

a  : a vehicle's license plates

b  : small stickers on a vehicle's license plates which show that the vehicle can legally be driven until a particular date

[count] computers : a piece of computer code that is used to identify a particular type of text so that the text can be arranged or shown in a certain way

[count] : tag question

: to put a tag on (something)

: to name or describe (someone or something) in a specified way : label

US, informal : to damage (someone else's property) by illegally writing or painting something (such as your name) on it : to write graffiti on (something)

[noncount] : a children's game in which one player is called “it” and chases the other players to try to touch one of them and make that player “it” — see also phone tag

[count] baseball : the act of causing a base runner to be out by touching the runner with the ball : the act of tagging a runner

: to touch (a player) in a game of tag

a  : to cause (a base runner) to be out by touching him or her with the ball

b  : to put your foot on a base and stay there until a fly ball is caught before you begin to run to try to reach the next base — often + up