Webster's Revised Unabridged Dictionary · 1913

Inboard

Inboard , adjective and adverb

1.
(Nautical) Inside the line of a vessel's bulwarks or hull; the opposite of outboard; as, an inboard engine; an inboard cargo; haul the boom inboard.
2.
(Mechanics) From without inward; toward the inside; as, the inboard stroke of a steam engine piston, the inward or return stroke.