tag¹ / tag/ • n. 1. a label attached to someone or something for the purpose of identification or to give other information. ∎  an electronic device that can be attached to someone or something for monitoring purposes, e.g., to deter shoplifters. ∎  a nickname or description popularly given to someone or something. ∎  a license plate of a motor vehicle. ∎  Comput. a character or set of characters appended to or enclosing an item of data in order to identify it.2. a small piece or part that is attached to a main body. ∎  a ragged lock of wool on a sheep. ∎  the tip of an animal's tail when it is distinctively colored. ∎  a loose or spare end of something; a leftover. ∎  a metal or plastic point at the end of a shoelace that stiffens it, making it easier to insert through an eyelet.3. a frequently repeated quotation or stock phrase. ∎  Theater a closing speech addressed to the audience. ∎  the refrain of a song. ∎  a musical phrase added to the end of a piece. ∎  Gram. a short phrase or clause added to an already complete sentence, as in I like it, I do.See also tag question.• v. (tagged, tag·ging) [tr.] 1. attach a label to: the bears were tagged and released. ∎  [tr.] give a specified name or description to: he left because he didn't want to be tagged as a soap star. ∎  attach an electronic tag to: [as n.] (tagging) laser tattooing is used in the tagging of cattle. ∎  Comput. add a character or set of characters to (an item of data) in order to identify it for later retrieval. ∎  Biol. & Chem. label (something) with a radioactive isotope, fluorescent dye, or other marker: pieces of DNA tagged with radioactive particles.2. [tr.] add to something, esp. as an afterthought or with no real connection: she meant to tag her question on at the end of her remarks. ∎  [intr.] follow or accompany someone, esp. without invitation: that'll teach you not to tag along where you're not wanted.3. shear away ragged locks of wool from (sheep).tag² • n. a children's game in which one chases the rest, and anyone who is touched then becomes the pursuer. ∎  Baseball the action of tagging out a runner or tagging a base: he narrowly avoided a sweeping tag by the first baseman. ∎  [as adj.] denoting a form of wrestling involving tag teams.See tag team.• v. (tagged, tag·ging) [tr.] touch (someone being chased) in a game of tag. ∎  (tag out) Baseball put out (a runner) by touching them with the ball or with the glove holding the ball: catching their fastest runner in a rundown and tagging him out. ∎ Baseball (of a base runner, or a fielder with the ball) touch (a base) with the foot: the short center fielder could field the ball and tag second base for a force out. ∎  [intr.] (usu. tag up) Baseball (of a base runner) touch the base one has occupied after a fly ball is caught, before running to the next base: when the ball was hit, he went back to the bag to tag up.

TAG. A term in LINGUISTICS for several types of structure in which one or more words are tagged on to a clause or sentence, including: (1) Continuation tags. Words and phrases used as shorthand at the end of a list: etc.; and so on; and so forth. (2) Questioning and commenting tags. Questions, questioning words, and commenting words that can be added to statements are common in formal conversation: ‘She's pretty, don't you think?’; ‘You'll pay me back tomorrow, OK?’; ‘It's difficult, I suppose’; ‘You know, it can't be easy for her.’ Such forms can usually be rearranged as standard questions and statements: Don't you think she's pretty?; I suppose (that) it's difficult. (3) Focusing and emphasizing tags. These usually restate the subject and sometimes the verb: ‘She's amazing, (is) my grandmother’; ‘My grandmother, she's amazing’; ‘She's amazing, she is’; ‘She comes here often, does Joan’ (a usage common in the North of England). See LATIN TAG, QUESTION TAG, TAG QUESTION.

tag
1. To mark in some distinctive fashion any node in a data structure that has been traversed. Using this technique precautions can be taken against revisiting nodes, e.g. in a circular list.

2. Short for tag field. A field that is used to discriminate between variants of the same type.

tag1 small pendent piece, orig. on a garment XIV (implied in tagged); ornamental pendant XVI; point of metal, etc. at the end of a lace; something appended to a piece of writing, etc., brief quotation XVIII. of unkn. orig.
Hence tag vb. XVI mark with a tag.

tag a brief and usually familiar quotation added for special effect; a much used quotation or stock phrase. The word in this sense is recorded from the early 18th century.