also offshore, 1720, "in a direction away from the shore," from off (prep.) + shore (n.). As an adjective in 19c., "carried on more than three miles from shore." American English use for "other than the U.S." is from 1948 and the Marshall Plan.
off-road
off-scouring
off-season
offset
offshoot
off-shore
offshoring
offside
off-site
offspring
off-stage