This paper addresses the relationship between the term ADHD and the object it purports to represent. While the most familiar linguistic position, Referential Theory, suggests that the term constitutes an etymological peg corresponding to a particular part of nature, there are other, arguably more sophisticated, philosophical approaches that point to an altogether more complex relationship. These approaches do not assume that "behaviour disorders," such as ADHD, are objective facts of nature, facts to which words can simply be affixed. Using the work of Wittgenstein, the intention here is to use the philosophy of language to destabilize not just the relationship between the term ADHD and the idea to which it applies, but also the coherence of the notion of ADHD itself.