Emily Dickinson Lexicon

PLY, v.t. [Fr. plier, to bend or fold, formerly written ployer whence employ; Arm. plega, W. plygu, It. piegare, Sp: plegar, Port. pregar, L. plico, Gr. πλεκω, to fold; Sax. pleggan, to play and to lie on; D. pleegen, to use, to exercise; Dan. plejer, to exercise, to perform an office, to tend, to nurse; G. pflegen, id.; Sw. pläga. That these words are from the root of lie, lay, is obvious, for in G. liegen, to lie, signifies also to ply, to apply. The prefix p may be used for the Teutonic be; be-liegen, to lie close, to bend to. See Lay and Lie.]

1. To lay on, to put to or on with force and repetition; to apply to closely, with continuation of efforts or urgency. And plies him with redoubled strokes. – Dryden. The hero from afar / Plies him with darts and stones. – Dryden. We retain the precise sense in the phrase to lay on, to put it on him.
2. To employ with diligence; to apply closely and steadily; to keep busy. Her gentle wit she plies. – Spenser. The wearied Trojans ply their shattered oars. – Dryden.
3. To practice or perform with diligence. Their bloody task, unwearied, still they ply. – Waller.
4. To urge; to solicit with pressing or persevering importunity. He plies the duke at morning and at night. – Shak.
5. To urge; to press; to strain; to force.