assailer

transitive verb

1. to attack physically and violently; assault
2. to attack with arguments, questions, doubts, etc.
3. to begin working on (a task, problem, etc.) with vigor and determination
4. to have a forceful effect on: a loud noise assailed her ears

Origin: ME assailen < OFr asaillir < VL assalire, for L assilire, to leap on < ad-, to + salire, to leap: see salient