c.1600, from Latin expungere "prick out, blot out, mark (a name on a list) for deletion" by pricking dots above or below it, literally "prick out," from ex- "out" (see ex-) + pungere "to prick, stab" (see pungent). According to OED, taken by early lexicographers in English to "denote actual obliteration by pricking;" it adds that the sense probably was influenced by sponge. Related: Expunged; expunging.