Answer :
Answer:
A final broad classification which is sometimes used to categorize nouns is the distinction between variable and non variable nouns.
Variable nouns are those which have a singular and a plural form, whereas invariable nouns don't. So count nouns are variable but mass nouns aren't.
However, there are some irregularities dotted throughout the system. A few count nouns, such as sheep and deer, have no actual marker of plurality and a plural sense.