What is Greek for speed?

There isn't one single perfect translation for "speed" in Greek, as the best word depends on the context. Here are a few options:

* Ταχύτητα (tachýtita): This is the most common and general word for "speed" in the sense of velocity or rate of movement.

* Ορμή (ormí): This means "impetus" or "momentum," and can be used when referring to speed with a sense of force or driving energy.

* Ταχύς (tachýs): This is an adjective meaning "fast" or "swift." You'd use it attributively, like "ταχύς δρομέας" (tachýs droméas) meaning "fast runner."

So, the best choice depends on what kind of speed you're talking about. For most general uses, ταχύτητα (tachýtita) is the appropriate word.