citrus fruit vs citrous fruit

citrus fruit and citrous fruit both are nouns.

Word	Noun	Adjective	Verb	Adverb
citrus fruit	Yes	No	No	No
citrous fruit	Yes	No	No	No

As nouns, citrus fruit and citrous fruit are synonyms defined as:

citrus fruit and citrous fruit: any of numerous fruits of the genus Citrus having thick rind and juicy pulp; grown in warm regions

Other synonyms of citrus fruit include citrus.

citrus fruit (noun)	citrous fruit (noun)
any of numerous fruits of the genus Citrus having thick rind and juicy pulp; grown in warm regions	any of numerous fruits of the genus Citrus having thick rind and juicy pulp; grown in warm regions