harm (n.) Look up harm at Dictionary.com
Old English hearm "hurt, pain; evil, grief; insult," from Proto-Germanic *harmaz (cognates: Old Saxon harm, Old Norse harmr "grief, sorrow," Old Frisian herm "insult; pain," Old High German harm, German Harm "grief, sorrow, harm"), from PIE *kormo- "pain." To be in harm's way is from 1660s.
harm (v.) Look up harm at Dictionary.com
Old English hearmian "to hurt, injure," from the noun (see harm (n.)). It has ousted Old English skeþþan (see scathe (v.)) in all but a few senses. Related: Harmed; harming.