ply one's trade

: to use or wield diligently

: to practice or perform diligently

: to keep furnishing or supplying something to

: one of several layers (as of cloth) usually sewn or laminated together

: one of the strands in a yarn

: one of the veneer sheets forming plywood

: to twist together

: the business of buying and selling or bartering commodities : commerce

: business, market

: dealings between persons or groups

: to give one thing in exchange for another

: to engage in the exchange, purchase, or sale of goods

: to make one's purchases : shop

: of, relating to, or used in trade

: intended for or limited to persons in a business or industry

: serving others in the same business rather than the ultimate user or consumer