I. ply 1 /plaɪ/ BrE AmE verb ( past tense and past participle plied , present participle plying , third person singular plies )
[ Date: 1300-1400 ; Origin: apply ]
1 . ply your trade literary to work at your business, especially buying and selling things on the street:
In some areas, drug dealers openly ply their trade on street corners.
2 . [I, T always + adv/prep] written if a ship, bus etc plies between two places or across a place, it does that journey regularly
ply between/across etc
Two ferries ply between Tripoli and Malta every day.
3 . ply for hire/trade British English to try to get customers or passengers, in order to do business:
Continental airlines ply for trade in the UK.
4 . [transitive] old use literary to use a tool skilfully
ply somebody with something phrasal verb
1 . to keep giving someone large quantities of food or drink:
The local people plied me with beer, until I could barely move.
2 . ply somebody with questions to keep asking someone questions
II. ply 2 BrE AmE noun ( plural ply ) [countable]
[ Date: 1500-1600 ; Language: French ; Origin: pli , from Old French plier ; ⇨ ↑ pliers ]
a unit for measuring the thickness of thread, rope, plywood etc, based on the number of threads or layers that it has:
a sweater in four-ply yarn