A simple fastener, for a door or window, consisting of a short bar that rotates about a pivot attached to the frame

Conservative. / Carefully planned and executed.

A small coin cell

A shirt fastened by a vertical column of buttons at the front.

plural of button-up

plural of button mushroom

(idiomatic) A nose with a small size and a relatively flat, round shape, usually considered to be dainty or cute in appearance. / (idiomatic) A person having such a nose.

(slang) The clitoris.

(slang) The clitoris. / (slang) The prostate (in relation to sexual stimulation through the rectum).

(transitive) To detain in conversation to the point of weariness; to bore; to buttonhole.