Combat
mid 16th century (originally denoting a fight between two people or parties): from French combattre (verb), from late Latin combattere, from com- ‘together with’ + battere, variant of Latin batuere ‘to fight’.
wiktionary
Borrowed from French, from Old French combatre, from Vulgar Latin *combattere, from Latin com-(“with”) + battuere(“to beat, strike”).
etymonline
combat (v.)
1560s, "to fight, struggle, contend" (intransitive), from French combat (16c.), from Old French combattre (12c.), from Late Latin combattere, from Latin com "with (each other)," see com-, + battuere "to beat, fight" (see batter (v.)). Transitive sense is from 1580s; figurative sense from 1620s. Related: Combated; combating; combatted; combatting.
combat (n.)
1560s, "a fight," originally especially "a fight between two armed persons" (later distinguished as single combat, 1620s), also in a general sense of "any struggle or fight between opposing forces," from French combat (see combat (v.)).