meddler (n.)

early 14c., "to mingle, blend, mix" (a sense now obsolete), from Old North French medler (Old French mesler, 12c., Modern French mêler) "to mix, mingle, to meddle," from Vulgar Latin *misculare (source of Provençal mesclar, Spanish mezclar, Italian mescolare, meschiare), from Latin miscere "to mix" (from PIE root *meik- "to mix").

From late 14c. as "busy oneself, be concerned with, engage in," and in the disparaging sense of "interfere or take part in inappropriately or impertinently, be officious, make a nuisance of oneself" (the notion is of meddling too much), which is the surviving sense of the word. From mid-14c. to c. 1700 it also was a euphemism for "have sexual intercourse." Related: Meddled; meddling.