(astronomy) A kind of altitude and azimuth instrument. The object end of the telescope is placed at right angles to the eye end, with a prism of total reflection at the angle, and the eye end constitutes a portion of the horizontal axis of the instrument, having the eyepiece at the pivot and in the center of the altitude circle, so that the eye has convenient access to both at the same time.

(rail transport, UK) An instrument installed in a cabinet, used in block signalling installations.

(literally) An object lacking sharp surfaces, especially as used to cause injury.

(finance, law) A document evidencing a debt; the debt so evidenced.

(music) an instrument that produces a concert pitch of F when a C is written in the music

(music) an instrument that either does not transpose, or transposes by an octave or multiple octaves.

(aviation) An airline selected by government to represent the country.

(aviation, usually in the plural) A device that measures and displays data concerning one or more aspects of the situation of an aircraft, such as its altitude, attitude, airspeed, etc.

(aviation) An approach (pre-landing procedure) using flight instruments for some or all navigation to the landing airport and runway, as opposed to one flown solely by visual reference to the ground.

plural of instrument approach