(a) A written communication, a letter; (b) a letter of authority or credentials; an authorization. …

Mus. (a) The lowest tone in the hexachordal scale; (b) the entire hexachordal system. …

Mus. An interval approximating half a whole tone. …

(a) An interval or a span of time elapsing between two specified points, events, etc.; (b) the amount or extent of time comprised by or contained within a specified period; -- often with gen. or of ph……