The suffix -ment forms nouns from verbs, e.g. entertain → entertainment.
A similar suffix exists in French (and -mente in other Romance languages) that forms adverbs from adjectives, e.g. sûr → sûrement, which comes from Latin mentus.
Is the English noun suffix related to (cognate with) French adverb suffix? If so, then how did it became v. → n. from adj. → adv.? If not, where does it come from?