Well, it's hard to say for sure - like you, Keemun, I haven't heard a firm definition. But usually it can be told following this criteria:
1. 3/4 (or 2/4 rarely) time [as you mentioned]
2. Light, playful - not always (c.f. Bruckner)! [as you mentioned, too]
3. Ironic, grotesque, jocund etc.
4. The third movement of a normally arranged post-classical symphony
5. Quick, prominent (allegro or something like that), and it's not the 1st nor the 4th
movement of such a symphony
6. By the title
7. The form of a complex three-part song (aba cdc aba, or extended)
That's what I think usually works.