Is it grammatically correct to put both of related nouns in plural form? Like:
- cards databases / databases of cards
- words variations / variations of words
- etc
Is it grammatically correct to put both of related nouns in plural form? Like:
In both of your examples, the first form is called a compound noun: the first noun modifies the second noun, in the same way that an adjective would. When you use a compound noun, the modifying noun is never pluralized.
card databases
word variations
In the second form, you are using a genitive form, indicated by the word of. With the genitive, you use the plural for the first word if there is more than one of the item that the first word describes. If there is only one of it, you use the singular form even if there are many items described by the second word.
a database of cards
two databases of cards.