(usually with the definite article) a breach, place which is hard to defend; a danger, requiring bravery

(computer security, of a system) Physically isolated from the Internet or some other unsecured network.

A space between the inner thighs of some people when standing upright with feet touching.

A turning lathe with a deep notch in the bed to allow turning a short object of large diameter.

(idiomatic) To expose oneself for the protection of something; to make defence against any assailing danger; to take the place of a fallen defender or supporter.

(networking, computer security) A network security measure that consists of ensuring that a secure computer network is physically isolated from unsecured networks, such as the public Internet or an unsecured local area network.

plural of gap junction

(music) A vocal technique in which certain tones out of a complete set of tones are omitted.

plural of gapped scale

(paleontology) An apparent gap in the tetrapod fossil record in the lower Mississippian.