ply
v.v. to travel a route regularly or to work hard at a job. You might use it to describe a boat moving back and forth or someone selling goods on the street.
v. to travel regularly over a route or to practice a trade or craft diligently. Often describes the repetitive movement of vessels or the persistent offering of goods or services.
Small boats ply the river throughout the summer.
The ferry continues to ply the waters between the two islands, providing a vital link for the local community.
Street vendors often ply their trade in the busy square, calling out to tourists and locals alike as they navigate the crowded walkways during the peak of the afternoon rush.
From Middle English pleit, plit, plite (“a fold, pleat, wrinkle; braid, strand in a braided cord, ply”), from Anglo-Norman pli, plei, pleit, and Middle French pli, ploy, ply (“a fold, pleat; joint in armour; situation, state”) (modern French pli (“a fold, pleat”)), from plier, ployer (“to bend, fold”), from plicāre (“to bend, fold, roll up”), from Proto-Indo-European *pleḱ- (“to fold, plait, weave”).
From Middle English plīen, pli, plie (“to bend, fold, mould, shape; to be flexible; to be submissive, humble oneself; to compel someone to submit”), from Anglo-Norman plier, plaier, pleier, ploier, and Middle French plier, ployer (“to bend, fold; to be submissive; to compel someone to submit”) (modern French plier, ployer), from Old French ploiier, pleier (“to fold”), from Latin plicāre (“to fold”); see further at etymology 1. The word is cognate with Catalan plegar (“to bend, fold”), Italian piegare (“to bend, fold, fold up”), Old Occitan plegar, plejar, pleyar (“to fold”) (modern Occitan plegar), Spanish plegar (“to fold”).
From apply; compare Middle English plīen, pli, plie, pleie (“to place (something) around, on, or over, to cover; to apply, use; to strive”), short for aplīen, applīen (“to combine, join; to attach; to assemble; to use, be of use; to allot; to apply; to inflict; to go; to ply, steer; to comply, submit”), from Old French applier, aplier, aploier (“to bend; to apply”), from Latin applicāre, present active infinitive of applicō (“to apply; to attach, join; to add”), from ad- (“to, towards”) + plicō (“to bend, fold, roll up”); see further at etymology 1.
The verb is transitive and typically takes a direct object such as 'a route', 'the waters', or 'a trade'.