• Linguistic geniuses such as Heinrich Schliemann have long fascinated many with their exceptional capabilities to master multiple languages on top of their own mother tongues. These individuals are believed to be able to extract the probabilistic, abstract patterns underlying a target form’s linguistic and frequency distribution in second language (L2) input—often with considerable efficiency and effectiveness. In the study of Second Language Acquisition (SLA), interest in such remarkable talent for picking up languages is by and large undertaken by the notion of “language aptitude” and its corresponding strands of research. That said, language aptitude remains one of the most confounded constructs in L2 individual differences research, especially from a definitional point of view.