What does "wherewith" mean?

Something with which; the means by which.

What is a synonym for "wherewith"?

Common synonyms include: ability, by, by means of, by virtue of, by way of, capacity.

/ʍɛɚˈwɪð/ adv, noun

adv, noun ·Uncommon ·Advanced level

Noun

1
Something with which; the means by which. archaic, uncountable, usually
"Hath not he wherewith [translating dequoy] to be beholding vnto this his killing vivacitie?"

Adverb

1
With which; with what. archaic, not-comparable
"Yee are the ſalt of the earth: But if the ſalt haue loſt his ſauour, wherewith ſhall it bee ſalted?"

"Nor is there any weapon of thought wherewith to defend."

From Middle English wherwith. By surface analysis, where + with.