I guess it's spontaneous order that leads to the sort of linguistic discrepancies presented below. Such natural formation is my guess for the reason that we don't have a 1:1 (bijective) mapping of words and meanings.
There are words that when used by certain groups of people mean something other than what you're used to? e.g. white person says "freak" they mean "goth" or "weird/strange person"...black person says "freak," they mean "promiscuous" or "slutty."
Nick pointed out that the Humanities has stolen words used in common parlance and given them ENTIRELY different meanings. e.g. ?????????. (you guys help me out here, I can't think of any).
This phenomenon is different than the one where people from different groups (usually geographically separated) use different words to refer to the same object. e.g. "coke" vs. "soda" vs. "pop" vs. "soda-pop." Personally, I laugh every time I hear someone refer to a "shopping cart" as a "buggy."
I'm sure these sorts of things happen in most other languages. I am fairly good at the recognizing the latter in Spanish. Por ejemplo, los cubanos no dicen "papaya" para referir a la fruta porque "papaya" significa la vagina. En su lugar, dice "la fruta bomba."
I have also noticed a little bit of the former in Spanish...En el Ecuador, "guagua" significa "bebé" cuando en las islas del mar caribe se usa "guagua" para un "autobús. Pero "autobús" se coloca entre el otro grupo también...algunos (como mexicanos) dicen "omnibus." España tiene sus propias palabras para bastante..."zumo" "ordenedor" "servicios," más.
I don't know nearly enough Swahili for examples, but I think there may be different words with the same meaning in Kiswahili. 1) Swahili is a second language learned by native speakers of many different languages so that they can communicate outside their native tongue. I would think this would bring many different words to mean the same thing. However, these different words may not be obvious to Swahili-speakers of different linguistic backgrounds (which may keep development of these slow). So far in my exploration of this language (which is cursory at best), the only word I know with 2 meanings is "ndege" which means "bird" and "plane."