Cognitive status in treatment studies is mainly based on spelling similarity, while a more integrated approach, taking into account the paradigmatic variable role, should be favoured in order to clarify the organisational principles of the mental lexicon. The two hidden initiation experiments presented here examine the role of etymology, i.e. Latin versus Greek, in advanced bilingual Greek and French. Two seed directorates were tested, with the same participants. In the direction of initiation L1 to L2, both types of stimuli led to translational and morphological initiation effects, while in the opposite direction only the primers of Greek etymological origin (L1) had statistically significant effects. The results demonstrate the role of morphology in the common lexico-semantic architecture of mental lexics and suggest a possible explanation for the asymmetry often found between the two initiation directions.