複数的英文：
[Grammar] the plural number; plurality

Not in accord with the rules of a prescriptive grammar.
不合语法的不符合规定的语法规则的

That is not, properly speaking, a dictionary, but a grammar.
严格说来;那不是一本词典,而是一本语法书。

Bad grammar tends irk teachers.
语法不好常使老师生气。

Heavens here is plural.
这里的天这个名词用的是复数形式。

Data is a plural noun.

The verb should be in the plural.
这个动词应用复数形式。

The number was fifty.
该数字为五十。

There is safety in numbers
人多势众

It was an irrational number.
这是一个无理数。