1620s, "one who loads (a ship)," agent noun from freight (v.). Meaning "a cargo vessel" is from 1839, American English.
Entries linking to freighter
freight v.
"to load (a ship) with goods or merchandise for shipment," mid-15c. variant of Middle English fraught (v.) "to load (a ship)," c. 1400; see fraught, and compare freight (n.). Figuratively, "to carry or transport," 1530s. Related: Freighted; freighting.