68. Inflection is a change in the form of a word to denote a different application or use.
Number is the form of a noun which shows whether it denotes one or more than one.
The singular number denotes one thing.
The plural number denotes more than one thing.
There are a few rules governing the formation of plurals which we must know, and these rules are of great assistance in correct spelling.
69. Most nouns form their plural by adding s—thus:
| boat | day | book | boy |
| boats | days | books | boys |
Long ago in early English all plurals were formed by adding es, and you will read in the first translation of the Bible, for instance, such words as bird-es, cloud-es. Later the e was dropped and s added to the singular without an increase of syllables. But when the singular ends in an s sound, the original syllable es is retained, for two hissing sounds will not unite.
70. So nouns ending in s, x, z, sh or soft ch, form the plural by adding es to the singular. These words end with a sound so much like that of s that we cannot pronounce the plural easily without making another syllable. Thus:
| class | tax | topaz | wish | ditch |
| classes | taxes | topazes | wishes | ditches |