"person who wanders about, idle vagrant, vagabond," 1660s, from tramp (v). Sense of "steamship which takes cargo wherever it can be traded" (as opposed to one running a regular line) is attested from c. 1880. The meaning "promiscuous woman" is from 1922. Sense of "a long, toilsome walk" is from 1786.
tramp (v.)
late 14c., "walk heavily, stamp," from Middle Low German trampen "to stamp," from Proto-Germanic *tremp- (cognates: Danish trampe, Swedish trampa "to tramp, stamp," Gothic ana-trimpan "to press upon"), from PIE *der- (1) "to run, walk, step" (see tread (v.)). Related: Tramped; tramping.