In linguistics, an expression is semantically ambiguous when it can have multiple meanings.
[2] The language itself is sometimes a contributing factor in the overall effect of semantic ambiguity, in the sense that the level of ambiguity in the context can change depending on whether or not a language boundary is crossed.
When a lexical ambiguity results from a single word having two senses, it is called polysemy.
When an ambiguity instead results from two separate words which happen to be pronounced the same way, it is called homonymy.
In practice, polysemy and homonymy can be difficult to distinguish.