Assailant

wiktionary

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From Old French asaillant, from the verb asaillir(“to jump on”), from Latin assaliō, itself from ad(“to, towards”) + saliō(“to jump”).

etymonline

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assailant (n.)

"one who assails," 1530s, from French assailant, noun use of present participle of assailir (see assail). Earlier in same sense was assailer (c. 1400).