v.tr. 1 call upon to appear, esp. as a defendant or witness in a lawcourt. 2 (usu. foll. by to + infin.) call upon (summoned her to assist). 3 call together for a meeting or some other purpose (summoned the members to attend). summon up (often foll. by to, for) gather (courage, spirits, resources, etc.) (summoned up her strength for the task). summonable adj. summoner n.
[ ME f. OF somondre f. L summonere (as SUB-, monere warn) ]