1835, Amer.Eng., back-formation from
loafer (1830), which often is regarded as a variant of
land loper (1795), a partial loan-translation of Ger.
Landläufer "vagabond," from
Land "land" +
Läufer "runner," from
laufen "to run" (see
leap). But OED finds this "not very probable."
Loafer, the type of shoe, is attested from 1939, originally a brand name (Fortnum and Mason Ltd., London).