Emily Dickinson Lexicon

FLAG, v.i. [W. llacâu, or llaciaw, to relax, to droop; llegu, to flag; L. flacceo; Sp. flaquear; Port fraquear, to flag; Ir. lag, weak. See Flaccid. The sense is primarily to bend, or rather to recede, to lag.]

1. To hang loose without stiffness; to bend down as flexible bodies; to be loose and yielding; as, the flagging sails. Dryden.
2. To grow spiritless or dejected; to droop; to grow languid; as, the spirits flag.
3. To grow weak; to lose vigor; as, the strength flags.
4. To become dull or languid. The pleasures of the town begin to flag. Swift.