Why is swim in the definite conjugation, while run is in the indefinite? Is there a rule here? It seems they should both be indefinite...
Because "futom" doesn't exist. So we can only say "futok".
Okay, thanks. But that begs the question, why can úsz be both definite and indefinite, while fut cannot? Aren't they essentially the same kind of verb?
The definite and indefinite forms of "úsz..." happen to be the same, in the first person singular only. Because it is an "ik" verb.
"Fut" is not an "ik" verb, it has different forms for the definite and the indefinite in the first person singular.
Aaah I see, that answers my question. Thanks!
They are both indefinite. But "úszom" is an "ik" type verb, ie. its third person singular form is "úszik". These verbs usually take an "-m" ending in the first person singular.