What part of speech is unbalances?

Unbalances can be categorized as a verb.

Parts of speech

1. unbalances is a verb, present, 3rd person singular of unbalance (infinitive).

Verb
unbalance - derange mentally, throw out of mental balance; make insane; "The death of his parents unbalanced him"
unbalance - throw out of balance or equilibrium; "The tax relief unbalanced the budget"; "The prima donna unbalances the smooth work in our department"