c.1300, "to drag along behind," from O.Fr. trailler "to tow," ult. from V.L. *tragulare "to drag," from L. tragula "dragnet," probably related to trahere "to pull" (see tract (1)). The meaning "follow the trail of" is first recorded 1590.
c.1300, "train of a robe," from the source of trail (v.). The meaning "track or smell left by a person or animal" is also from 1590. Meaning "path or track worn in wilderness" is attested from 1807.