Which is correct? : Both is nice. / Both are nice.
If there is some word behind 'both' like 'both women', it would be 'Both women are pretty.' But if there is no word, 'both' is used as singular noun or plural noun?

Question

Which is correct? : Both is nice. / Both are nice.
If there is some word  behind 'both'  like 'both women', it would be 'Both women are pretty.' But if there is no word, 'both' is used as singular noun or plural noun?

Answer

I think so. 
"Both are nice" is correct and there is a same word in negative form that it is " Neither ".
you can use both forms using "Neither" like:
Neither of them is red. ( here we have 2 pens. one of them is black and the other one is blue)
Neither of them are red. ( " " " )

Answer

"Both" refers to two things, so your only option is plural: "Both are..."

Answer

Both are nice . "Both" is plural, so the verb must also be plural.

Answer

I think it should be plural. 
Both are nice. 
-Both +plural verb
-Both(the)+plural noun+plural vervb
-Both of +plural noun +plural verb