Someone dressed up in a zoot suit, aka zooter. Not necessarily a gangster, but always associated with cholos. The style originated in El Paso, TX back in the 1930s. Hence, El Paso is now known to many Chicanos as "El Chuco ."
In common usage, generally any young hispanic/Mexican-American males perceived (through similarity of garb, haircuts, etc.) to be members of a street gang. Actual gang in Southern California dates back to and rivals the Hell's Angels
"I think those Mexican guys standing on the corner are probably pachucos."
1. A hispanic or spanish or mexican or latino or chicano man that defends his barrio from outsiders.
2. A hispanic or spanish or mexican or latino or chicano man that fights to preserve his cultures way of living whether that be with guns, knives, or political influence
(2.) Texans and Californians are taking over Santa Fe, New Mexico with the help of greedy developers, but not if we can get a pachuco into office to defend the barrio!