"citron" in the noun sense
1. citron
large lemonlike fruit with thick aromatic rind usually preserved
2. citron, citron tree, Citrus medica
thorny evergreen small tree or shrub of India widely cultivated for its large lemonlike fruits that have thick warty rind
Source: WordNet® (An amazing lexical database of English)
Princeton University "About WordNet®."
WordNet®. Princeton University. 2010.
View WordNet® License