Keep a stiff upper lip

What is Keep a stiff upper lip?

Keep a stiff upper lip definition and meaning on Dictionary terms:
either of the two fleshy parts or folds forming the margins of the mouth and functioning in speech.
Usually lips. these parts as organs of speech: I heard it from his own lips.

a projecting edge on a container or other hollow object: the lip of a pitcher.
a liplike part or structure, especially of anatomy.
any edge or rim.
the edge of an opening or cavity, as of a canyon or a wound: the lip of the crater.
Slang. impudent talk; back talk: Don’t give me any of your lip.
Botany. either of the two parts into which the corolla or calyx of certain plants, especially of the mint family, is divided.
Zoology. a labium. the outer or the inner margin of the aperture of a gastropod’s shell.

Music. the position and arrangement of lips and tongue in playing a wind instrument; embouchure.
the cutting edge of a tool.
the blade, at the end of an auger, which cuts the chip after it has been circumscribed by the spur.
(in a twist drill) the cutting edge at the bottom of each flute.

of or relating to the lips or a lip: lip ointment.
characterized by or made with the lips: to read lip movements.

superficial or insincere: to offer lip praise.

verb (used with object), lipped, lip