Fabienne Martin
, Yining Nie
, Artemis Alexiadou 
This paper discusses the morphosyntax and semantics of locative prepositions in French, with a particular focus on the prefix de- in complex prepositions (e.g., en dessous de [in from.under of] ‘below’) and in axial nominalizations (e.g., le dessous de [the from.under of] ‘the bottom part/region of’). We propose that in these formations, de-, which developed historically from an ablative marker, retains a Source semantics and lexicalizes the function project, which defines the region outward from the axial part of an object (Matushansky & Zwarts, 2019). We support our analysis with a corpus study on French child data showing that children acquiring L1 French tend to overuse de- in transitive contexts, overtly expressing conceptual structure that is typically implicit in the standard adult language, but replicating patterns present in Old and Medieval French.