Etymology From high + five. The five refers to the five fingers of each hand.
1
To slap high fives.
Like a lot of my fellow passengers — indie-rock fans who had signed up for a three-day voyage full of bands and beverages — I’d never been on a cruise before. So I don’t know whether most of them begin with a staff member high-fiving each and every person who comes off the gangway.2012 March 30, Joe Levy, “Rockers at Sea”, in The New York Times: