<p><strong>Adjective</strong></p><ul><li>Located nearer the longitudinal axis or center, as of an airplane: the inboard section of a wing.</li><li>Located inside a hull or aircraft: a motorboat with an inboard engine.</li><li>(Of a motorboat) having the motor inboard.</li></ul><p><strong>Adverb</strong></p><ul><li>Inside or toward the longitudinal axis or center of a hull, aircraft, machine, etc.</li></ul><p><strong>Noun</strong></p><ul><li>An inboard motor.</li><li>A boat equipped with an inboard motor.</li></ul>