There are three numbers: singular, plural, and double.
The following is a rule (but there are many exceptions from this rule):
- The plural of a feminine noun ending with ה is formed by replacing ה with ות.
- The plural of a noun ending with ות is formed by replacing ות with יות.
- The plural of a noun ending with ית is formed by replacing ית with יות.
- The plural of a noun ending with ת but not with ות or ית is sometimes formed by replacing ת with ות, but this case has many exceptions.
- The plural of some nouns (especially masculine) ending with ה is formed by replacing ה with ים.
- The plural of the rest nouns (mainly masculine) not ending with ה is formed by adding ים at the end of the word.
Because the rule above has many exceptions, it is possible to identify whether the plural of a given noun ends with ות or with ים only by consulting a dictionary.
Double number forms are the same as plural. But double number means two things instead of an indefinite plural number.
Accordingly this book only the following words have double number:
- names of measures and numbers;
- words denoting pair-things (such as hands of a man).