出典:Wiktionary
c. 1200, from Middle English therwith, from 古期英語 þǣrwiþ (“therewith, in return, in exchange, against”), equivalent to there + with. Cognate with Danish derved (“therewith”), Swedish därvid (“therewith, thereby”). Parallel with Dutch daarmee, German damit (“therewith”), though etymologically different. See also theremid.
therewith (not comparable)