triple time; three-four time
Musical term for a meter with three beats per measure, such as 3/4 or 3/8 time.
This piece is written in triple time.
three essential elements; three important requisites
Idiomatic use, almost always in the set phrase 三拍子揃う (to have all three essential qualities) or 三拍子揃った (complete in all three respects).
See also: 三拍子揃う
He is an actor who has all three: good looks, talent, and personality.