noun

1. a piece of cloth or bunting, often attached to a staff, with distinctive colors, patterns, or symbolic devices, used as a national or state symbol, as a signal, etc.; banner; standard; ensign
2. Now Rare long feathers or quills, as on a hawk
3. the tail of a deer
4. the bushy tail of certain dogs, as setters and some hounds
5. something, as a tab of metal or cardboard, that is attached to a card, folder, etc. so that it may be found easily, as in a file
6. Comput. a character, symbol, etc. used to mark data or a record for special attention
7. Music any of the lines extending from a stem, indicating whether the note is an eighth, sixteenth, etc.

Etymology: LME flagge < flag, in obs. sense “to flutter”

transitive verb flagged, flagging flag′·ging

1. to decorate or mark with flags
2. to signal with or as with a flag; esp., to signal to stop: often with down
3. to send (a message) by signaling
4. to mark with or as with a flag ( & ) to flag a word for deletion