Monosemy is the absence of semantic ambiguity in language, i.e. only having one meaning per word. The majority of natural human languages are polysemous, i.e. having more than one meaning per word. The artificial language Lojban and its predecessor Loglan represent attempts at creating monosemous languages. Monosemy is important for translation and semantic computing.
References
Monosemy Wikipedia(Text) CC BY-SA