Putative

Putative \PYOO-tuh-tiv\ , adjective;
1. Commonly regarded as such; reputed; supposed

This word dates to the mid-15th century from Middle French putatif, which derives from Latin putativus ("supposed"). The Latin word dates back to the 200's from putatus, the past participle of putare wich originally meant " to prune", but more recently meant "think, suppose, count, reckon."
This word made its entry into the English language as putative marriage, which was a union that was legally invalid, but contracted in good faith by at least one party.

Random fact: putative is a long-lost cousin of pave, as in "to cover with pavement".
Both words ultimately derive from Proto-Indo-European *pau-, which means "to cut, strike, stamp." The former became putare in Latin, while the latter became pavire ("to beat, ram, tread down").