Supremum, in mathematics, the least upper bound of a partially ordered set

Stand up paddle surfing

A shortened version of the word "supervisor"

Scottish Unionist Party (modern), established in the mid 1980s

Sailors' Union of the Pacific

Elision of "What's up" - when used as slang for "whats up" or "How are you doing?" or "hello"

SUP Fabrik or Sup Fabrik, a Russian internet company

Stanford University Press

Selective Ultraviolet Phototherapy

Socialist Unity Party

<sup></sup>, an HTML tag used to put a character as a superscript