late 15th century: from Latin factum, neuter past participle of facere ‘do’. The original sense was ‘an act’, later ‘a crime’, surviving in the phrase before (or after) the fact. The earliest of the current senses (‘truth, reality’) dates from the late 16th century
15世紀後半。ラテン語 factum から。facere「行う」の中性過去分詞。原義は「行為」で、のちに「犯罪」(before (after) the fact という句に残る)。現在の意味のうち最も早いもの(「真実、現実」)は16世紀後半から。