high five

from The Century Dictionary.

• noun See cinch, 4.

from the GNU version of the Collaborative International Dictionary of English.

• See cinch (the game).
• a celebratory or mutually congratulatory gesture between two persons performed by each slapping the other's raised right hand. Also used as a verb.

from Wiktionary, Creative Commons Attribution/Share-Alike License.

• noun A gesture of celebration or victory in which two people slap their hands together at shoulder height or higher.
• verb To slap high fives.

from WordNet 3.0 Copyright 2006 by Princeton University. All rights reserved.

• noun a gesture of greeting or elation; one person's upraised palm slaps the upraised palm of another person