Inflection is the change in a verb or noun that helps it to function better and add clarity in a sentence.
Inflection in a noun has to do with number. The plural form of most words simply involves adding an -s to the end, but there are plenty of words that change completely, and there are some that do not change at all from singular to plural. Following are just a few of the many nouns that do not have the simple -s form.
Examples of nouns that get an -es: church, fox, waltz, bus, box, dress, quiz
Examples of nouns that are identical in both singular and plural: fish, moose, sheep, aircraft, offspring, species, deer
Examples of nouns that change instead of using an -s: octopus, octopi; goose, geese; person, people; cactus, cacti; mouse, mice; man, men; child, children
Inflection in a verb has to do with tense. The three basic and most used tenses in English are past, present and future. These simple changes in verb tense add clarity to a sentence without adding more words.
“Timothy had pizza for lunch and will have pot roast tonight.”
“I was in the basement. I am in the kitchen. I will be in the garage.”