Etymology: (1300–50; ME plien < MF plier to fold, bend, var. of ployer, OF pleier < L plicāre to fold; see fold1)
Definition of 'ply'
Princeton's WordNet
1. (noun)ply one of the strands twisted together to makeyarn or rope or thread; often used in combination "three-ply cord"; "four-ply yarn"
2. (verb)ply (usually in combinations) one of several layers of cloth or paper or wood as in plywood
3. (verb)provide, supply, ply, cater give what is desired or needed, especially support, food or sustenance "The hostess provided lunch for all the guests"
4. (verb)ply 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
5. (verb)ply to employ diligently; to use steadily
6. (verb)ply to practice or perform with diligence; to work at
8. (verb)ply 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