absent: [14] Absent is based ultimately on the Latin verb ‘to be’, esse. To this was added the prefix ab- ‘away’, giving Latin abesse ‘be away’; and the present participial stem of abesse was absent-. Hence, via Old French, the adjective absent and the noun absence. It has been conjectured, incidentally, that the present stem used for Latin esse was a descendant of Indo-European *sontos ‘truth’, from which English sooth comes. [absent etymology, absent origin, 英语词源]