Weak inflection

Okay kiddo, so you know how some words can change a little bit when we add something to them? Like when we add -ed to the end of "jump" and it becomes "jumped"? That's called an inflection. Some languages, like Spanish and Latin, have lots of inflections to change the meaning of a word. But in English, we don't have as many inflections as some other languages.
But sometimes, when we add something to an English word, it doesn't change very much at all. That's called a weak inflection. It's like when we add -s to "dog" to make "dogs," the word only gets one extra letter and it sounds almost the same. Not all English words have weak inflections, but they are pretty common.