late 14c., from Old French total (14c.), from Medieval Latin totalis "entire, total" (as in summa totalis "sum total"), from Latin totus "all, all at once, the whole, entire, altogether," a word of unknown origin. Total war is attested from 1937 (William Shirer), in reference to a concept developed in Germany.
early 15c., "mighty, very powerful, possessed of inherent strength," from Latin potentem (nominative potens) "powerful," present participle of *potere "be powerful," from potis "powerful, able, capable; possible;" of persons, "better, preferable; chief, principal; strongest, foremost," from PIE root *poti- "powerful; lord." Meaning "having sexual power, capable of orgasm in sexual intercourse" (of men) is recorded by 1893.