This paper takes the papers in this special collection as a starting point and raises issues concerning key terms, with particular emphasis on incidental. It is argued that there is no clear way to show that a word has been learned incidentally, if one means that specific attention is not drawn to that word either by some external force or by the learner. I further argue that, to understand vocabulary learning, linguists cannot limit the investigation to word meaning. Essential to a study of the lexicon is the study of syntax—in particular, the incorporation of syntactic subcategorizations. Taking all of these factors into account, a more nuanced approach to the study of incidental vocabulary learning is needed.