Onomasiology is an appropriate methodology for discovering and analysing historical scientific and technical neology. Since it encompasses the whole of a changing vocabulary, it brings out the overall tendencies of lexical change. Firstly, attitudes toward onomasiology in terminology and neology are reviewed, before proceeding to an analysis of the description of the apricot tree in four French encyclopaedic dictionaries of the eighteenth century. This onomasiological demonstration sheds light on how French developed academic discourse in botany, above and beyond neology.