1. A dirty or untidy condition: "Our apartment was left in a terrible mess after the party."
2. A chaotic, confused, or troublesome state or situation: "The government plan turned out to be a complete mess."
3. Someone, or something, in a confused, dirty, or untidy condition.
4. A place where, or a time when, a group of people; especially, members of the military forces, have meals together.
5. A serving, or quantity, of food; especially, of soft or soggy food.
6. Etymology: "food for one meal, pottage", from Old French mes, "portion of food, course at dinner"; from Late Latin missus, "course at dinner"; literally, "placing, putting (on a table, etc.)"; from mittere, "to put, to place"; from Latin mittere. "to send, to let go".

The sense of "mixed food" led to the contemptuous use for "jumble, mixed mass" (1828), and the figurative sense of "the state of confusion" (1834), as well as "a condition of untidiness" (1851).

The meaning "communal eating place"; especially, a military one, is first known in 1536, from an earlier sense of "company of people eating together" (c.1420); originally, a group of four.

Messy or "untidy" is from 1843. To mess with, "to interfere, to get involved" is from 1903; mess up, "make a mistake, get in trouble" is from 1933, both originally, colloquial American English.