A lot vs. Alot: 9 Grammatical Pitfalls
1953, "experimental theater productions in New York City," from off (adv.) + Broadway. Even more experimental off-off-Broadway is attested from 1967.
A descriptive term for part of the theatrical community of New York City that presents small-scale, often experimental dramas. The costs of off-Broadway productions are generally much lower than those of Broadway plays.