One who has a stiff upper lip displays fortitude in the face of adversity, or exercises great self-restraint in the expression of emotion. The phrase is most commonly heard as part of the idiom "keep a stiff upper lip", and has traditionally been used to describe an attribute of British people, who are sometimes perceived by other cultures as being unemotional. A sign of weakness is trembling of the upper lip, hence the saying keep a stiff upper lip. When a person's upper lip begins to tremble, it is one of the first signs that the person is scared or shaken by experiencing deep emotion.

Stiff Upper Lip is an album by Australian hard rock band AC/DC. It was the band's thirteenth internationally released studio album and the fourteenth to be released in Australia. The album was co-produced by George Young, older brother of Malcolm and Angus Young. The album was re-released in the US on 2007 as part of the AC/DC Remasters series. It was re-released in the UK in 2005.