The strict, literal, dictionary definition of a word is called the "denotation."
This should be distinguished from other, somewhat different definitions of the same word that may be in use, which we would call the "connotation." Connotations refer to meaning which the public begins to ascribe to words.
You see this sort of thing happen to words all the time, especially as the younger generation begins to use certain words in new ways. For example, a few years ago the word "radical" took on a new meaning. It's denotation (actually one of it's denotations") is "different from the usual or traditional." Young people began using the word to mean something along the lines of "that's pretty interesting."
It would be fascinating to find out how words begin to suddenly take on new shades of meaning like that.