to ply is a form of:

Ply



ENGLISH MEANING
noun
1.
A fold; a plait; a turn or twist, as of a cord.
verb
1.
Bent; turn; direction; bias.
2.
(TRANSITIVE) To lay on closely, or in folds; to work upon steadily, or with repeated acts; to press upon; to urge importunately; as, to ply one with questions, with solicitations, or with drink.
3.
(TRANSITIVE) To employ diligently; to use steadily.
4.
(TRANSITIVE) To practice or perform with diligence; to work at.
5.
(INTRANSITIVE) To act, go, or work diligently and steadily; especially, to do something by repeated actions; to go back and forth; as, a steamer plies between certain ports.
6.
(INTRANSITIVE) To work to windward; to beat.
1.
To bend, to yield
2.
To bend