adverb
(nautical) In the middle of a ship, either longitudinally or laterally.
(nautical) Usually in the line of the keel, but sometimes halfway between bow and stern; often contracted to “midships.” (FM 55-501).
(figuratively) On the flank, at a vulnerable place.
interjection
A helm order, normally shortened to midships!, to centre the helm in the line of the keel.