Misspelling of dialogue tag.

(agriculture) to attach an ear tag to the ear of an animal.

(transitive) To affix a label to (potentially dangerous machinery) to indicate why it has been shut down. To avoid accidents, only the person who affixed the label is authorized to remove it and restart the machinery.

A sport in which players try to shoot the opposition using an infrared-sensitive gun.

(biochemistry) A short peptide, protein domain, or entire protein that can be fused to a target protein of interest to create a fusion protein.

A sport, resembling rugby league and touch football, in which pulling an adhesive tag from a player's belt takes the place of full-contact tackles.

(grammar) The "tag" at the end of a tag question

(idiomatic) A situation in which a person unsuccessfully attempts to contact another person by telephone and leaves a message instead, and in which the second person then unsuccessfully attempts to return the initial call and leaves a message for the first person, and so on as if the two are playing a game of tag in which the most recent person to have been left with a message is now designated as "it" (i.e. as the player now obliged to chase the other and to attempt anew to make contact).

(chiefly public transport) To hover an RFID device such as a smartcard over a receiver, often with a graphical user interface, in order to confirm the end of use or one's exit from the vehicle.

The very end. / Something left over.