'excitement' ultimately comes from Latin 'excitare' (frequentative of 'exciō'), where 'ex-' meant 'out' and 'citare'/'ciō' meant 'to rouse or summon'.

'excitare' passed into Old French as a form like 'exciter' and then into Middle English as 'exciten/ excite', with the noun-form developing into modern English 'excitement'.

Originally it meant 'to rouse, call forth, or stir up'; over time the noun came to denote the state of being stirred emotionally—i.e., enthusiasm, thrill, or agitation.