The Ugly One seems promising to me.
But did it mean that before the film, or only after? Remember, GBU has had a tremendous influence, both on culture and language. Of course, now "Tuco" can mean "the ugly one" because that's how the character with that name was identified in the movie.
Could it just be a nickname, a shortened affectionate version of a formal name that means nothing, like something a grandfather/mother would call a grandson/son etc., etc., , something along the lines of Tuco a "nick" version of Benedicto?
That could very well be, Cigar Joe. In fact, I think you may have hit the nail in the head. In Spanish, given names are altered when referring to little boys or girls. For example, the name Pedro (Peter in English) can be altered to mean "Little Peter" in a number of ways, such as "Pedrito", "Pedrete", Pedrillo, Pedruco, etc. It is therefore possible that the name Benedicto would have been altered to "Benedictuco" to refer to "Little Benedicto", which ended being "Tuco" for abbreviation.
1- a) (Latin American expression) maimed, limbless, lacking a finger or a hand.
That could very well be, Cigar Joe. In fact, I think you may have hit the nail in the head. In Spanish, given names are altered when referring to little boys or girls. For example, the name Pedro (Peter in English) can be altered to mean "Little Peter" in a number of ways, such as "Pedrito", "Pedrete", Pedrillo, Pedruco, etc. It is therefore possible that the name Benedicto would have been altered to "Benedictuco" to refer to "Little Benedicto", which ended being "Tuco" for abbreviation.Now, being Spanish, that would make complete sense to me!!!!! However, there is only one small region in Spain (Cantabria) where "uco" and "uca" are being used for that purpose (no idea about Mexico). And, coincidentally, it was in Laredo (Cantabria) where Leone filmed "The Colossus of Rhodes". Does someone see a connection here?
http://en.wikipedia.org/wiki/Spanish_nameHere's a wikipedia article which mentions the name Tuco: if you go down to the section Spanish hypocoristics and nicknames, it mentions Tuco as a diminutive of Alberto. No mention of Benedicto, although frankly that sounds a lot closer to Tuco than Alberto.