citrous fruit vs citrus fruit

citrous fruit and citrus fruit both are nouns.

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

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

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

Other synonyms of citrous fruit include citrus.

citrous fruit (noun)	citrus 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