A waltz is a dance in 3/4 time. It has a heavy accent on the 1st beat, Well not accent, but stress. This makes it different to other 3/4 dances, such as the minuet and allemande, which do not have heavy 1st beats.
Tchaikovsky did a waltz in 5/4 time. Hope that adds to the confusion ...
Again, most piano pieces called a waltz aren't meant to dance to.Prometheus