What is the X in X-mas?
late 15c., "a revoking" (of a grant, etc.), from Old French réclamacion and directly from Latin reclamationem (nominative reclamatio) "a cry of 'no,' a shout of disapproval," noun of action from past participle stem of reclamare "cry out against, protest" (see reclaim). From 1630s as "action of calling (someone) back" (from iniquity, etc.); meaning "action of claiming something taken awat" is from 1787. Of land from 1848.