formerly also enterfere, mid-15c., enterferen, "intermingle or mix (different things), interpose," also "to interfere," from Old French enterferer "exchange blows, strike each other," from entre- "between" (see entre-) + ferir "to strike," from Latin ferire "to knock, strike," related to Latin forare "to bore, pierce" (from PIE root *bhorh- "hole"). Compare punch (v.), which has both the senses "to hit" and "to make a hole in").
Figurative sense of "to meddle with, oppose unrightfully" is from 1630s. Related: Interfered; interfering. Modern French interférer is from English.
late 14c., "serve up (food) in portions," from mess (n.). Intransitive meaning "to share a mess, take one's meals in company with others" is from 1701; that of "make a mess of, disorder" is by 1853. Related: Messed; messing. To mess with "interfere, get involved" is by 1903; to mess up "make a mistake, get in trouble" is from 1933 (earlier "make disorderly, make a mess of," by 1892), both originally American English colloquial.
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.