loathe: [OE] Loathe originated as a derivative of the adjective loath or loth [OE]. This originally meant ‘hostile’ or ‘loathsome’, and goes back to a prehistoric Germanic *laithaz, which also produced Swedish led ‘fed up’ and German leid ‘sorrow’, and was borrowed into the Romance languages, giving French laid and Italian laido ‘ugly’.
loathe (v.)
Old English laðian "to hate, to be disgusted with," from lað "hostile" (see loath). Cognate with Old Saxon lethon, Old Norse leiða. Related: Loathed; loathing.