naco adj. common, ordinary, plebeian, unfashionable, vulgar. (source: Double-Tongued Dictionary)
Further reading
What kind of book do people ask for most often in prison? Romance novels? No. The Bible? No. The most requested books by far are … dictionaries! A number of volunteer organizations gather and distribute used dictionaries to help inmates with...
Twice a day the River Thames recedes, revealing a muddy shoreline. Hobbyists known as mudlarks stroll the surface searching for objects that have found their way into the river over the centuries, everything from ancient Roman jewelry to modern...
In Mexico, a very derogatory / racist reference to a poor person (invariably of Indian appearance).
it can also be used for fun, not only to offend
usu used like ‘que naco’ or ‘que naca’ for a girl.