Within linguistics a word class is defi ned in grammatical terms as a set
of words that exhibit the same syntactic properties. In this paper the aim
is to argue that the meanings of different word classes can be given a
cognitive grounding. It is shown that with the aid of conceptual spaces,
a geometric analysis can be provided for the major word classes. A universal
single-domain thesis is proposed, saying that words in all content
word classes, except for nouns, refer to a single domain.