Intuitive systems are usable systems. Design guidelines advocate intuitiveness and vendors claim it - but what does it mean for a user interface, interactive system, or device to be intuitive? A review of the use of the term 'intuitive' indicates that it has two distinct but overlapping meanings, namely intuitiveness based on familiarity and intuitiveness reflecting our embodiment (and frequently both). While everyday usage indicates that familiarity means either a passing acquaintance or an intimacy with something or someone, it will be concluded that familiarity might best be equated with 'know-how', which in turn is based on a deep, often tacit, understanding. The intuitive nature of tangible user interfaces will in turn be attributed to embodiment rather than tangibility per se. Merleau-Ponty writes that it is through our bodies that we 'prehend' the world. A number of disciplines now regard action-perception as so closely coupled that they are better considered as a dyad rather than separately. A modified treatment of action-perception coupling is proposed, with familiarity providing an epistemic core, as the basis of intuitiveness.