Definition of "Ply" :
noun: (usually in combinations) one of several layers of cloth or paper or wood as in plywood
noun: one of the strands twisted together to make yarn or rope or thread; often used in combination
verb: use diligently
"Ply your wits!."
verb: give what is desired or needed, especially support, food or sustenance
verb: wield vigorously
"Ply an axe."
verb: join together as by twisting, weaving, or molding
verb: travel a route regularly
"Ships ply the waters near the coast."
verb: apply oneself diligently
"Ply one's trade."