Noun

(en noun)

(obsolete) An opening; a recess or chamber.

* Chapman

the cave's inmost overture

(obsolete) disclosure; discovery; revelation

* Shakespeare

It was he / That made the overture of thy treasons to us.

(often in plural) An approach or proposal made to initiate communication, establish a relationship etc.

* {{quote-news

, year=2012 , date=April 23 , author=Angelique Chrisafis , title=François Hollande on top but far right scores record result in French election , work=the Guardian citation , page= , passage=Sarkozy gave a defiant speech, going on the offensive and betraying no hint of having been beaten. He styled the result as a "crisis" vote, by a French population which was "suffering". In a clear overture to Le Pen's voters, and the extreme-right motto of loving France, he said: "I call on all French people who put love of their country above partisan considerations, to unite and join me."}}

* 1994 , Nelson Mandela, Long Walk to Freedom , Abacus 2010, p. 20:

My mother had no choice; one did not turn down such an overture from the regent.

(Scotland) A motion placed before a legislative body, such as the General Assembly of the Church of Scotland.

(music) a musical introduction to a piece of music.

Noun

(en noun)

An opening; an open space; a gap, cleft, or chasm; a passage perforated; a hole; as, an aperture in a wall.

* Gilpin

an aperture between the mountains

* Owen

the back aperture of the nostrils

(optics) Something which restricts the diameter of the light path through one plane in an optical system.

(astronomy, photography) The diameter of the aperture (in the sense above) which restricts the width of the light path through the whole system. For a telescope, this is the diameter of the objective lens. e.g. a telescope may have a 100 cm aperture.

(spaceflight, communications) The (typically) large-diameter antenna used for receiving and transmitting radio frequency energy containing the data used in communication satellites, especially in the geostationary belt. For a comsat, this is typically a large reflective dish antenna; sometimes called an array .

(mathematics, rare, of a right circular cone) The maximum angle between the two generatrices.

If the generatrix makes an angle ? to the axis, then the aperture is 2?.