The article reports a study that investigated ideas about critical thinking as held by academics working in three disciplines: history, philosophy and cultural studies.  At least seven definitional strands were identified in the informants' commentaries, namely critical thinking: (i) as judgement; (ii) as skepticism; (iii) as a simple originality; (iv) as sensitive readings; (v) as rationality; (vi) as an activist engagement with knowledge; and (vii) as self-reflexivity.  This multiplicity of meanings is thought to have important implications for university teaching and learning.  The design of the study and the conclusions drawn from it draw heavily on Wittgenstein's idea of meaning as use.