Withstood is a verb. The verb is the part of the sentence that is conjugated and expresses action and state of being.

Whats the definition of withstood?

transitive verb. 1a : to stand up against : oppose with firm determination especially : to resist successfully.

Is debatable a noun or adjective?

debatable adjective - Definition, pictures, pronunciation and usage notes | Oxford Advanced Learner's Dictionary at OxfordLearnersDictionaries.com.