203 Free-for-all

(PW) mayhem, disorder

When the teacher left for a meeting, it was a free-for-all in the classroom.

(MW) Function: noun  Date: 1881

a competition, dispute, or fight open to all comers and usually with no rules : brawl; also : a chaotic situation resembling a free-for-all especially in lacking rules or structure

— free–for–all adjective

(free) n.

A disorderly fight, argument, or competition in which everyone present participates. See Synonyms at brawl.

Informal a disorganized brawl or argument, usually involving all those present

(phraseFinder)

Originally, a "race or competition" (Webster's 2nd, unabridged) that anyone is free to enter. Later, a fight that everyone joins in.