"We use the dictionary to check the definition."
Translation:Ni uzas la vortaron por kontroli la difinon.
I don't understand why there needs to be a "por" before "kontroli" in this sentence. Wouldn't it translate to "for to check"?
No it wouldn't translate that way, you must remember that languages don't translate directly word for word.
Ni uzas la vortaron por kontroli la difinon.
Ask yourself: What are they using the dictionary for?
for checking (to check) the definition.
Edit: better English
Please note that "to control" translates to "regi" in Esperanto, not "kontroli". False friends. :-)
"kontroli" means "to check" in the sense of examining, verifying.
Not ambiguous but wrong in the sense that you said, in English, that you used the dictionary to "control" the definition.
You used the wrong word in English.