Green’s Dictionary of Slang

714s n.

[? the digits imprinted into the pill]

(US drugs) methaqualone.

1977		L. Young et al. Recreational Drugs.
1981		D.E. Miller Bk of Jargon 338: 714s: Quaaludes (Methaqualone).
2001		ONDCP Street Terms 1: 714s — Methaqualone.