Other forms: high fives; high fiving; high fived
When someone says, "Up top!" and gives a congratulatory slap to your upraised palm, that's a high five.
If you sink a three-point shot in basketball, win an award, or get an A on an exam, you may get high fives from teammates, friends, a coach, or a teacher. Anyone yelling "Congratulations!" as they approach with a hand in the air probably wants to bestow a high five. They might also say, "Up high!" or "Give me five!" The five is from five fingers on a hand, and the term was originally 20th-century basketball slang.