The aim of the paper is to discuss vagueness of denominal adjectives in English
in their qualitative usage. Semantic indeterminacy will be illustrated for selected
denominal adjectives with the suffi x –ial, focusing on the lexeme professorial. The
range of the qualitative senses of such adjectives will be exemplifi ed by sentences
culled from COCA and other linguistic corpora. It will be argued that typicality
effects (as discussed by Lakoff 1987) are relevant to the identifi cation (and
fl exibility) of meanings of denominal adjectives.