OK this works. using prompt replace all "words" with "things" in the AI popup shown in the screenshot above when you select the text:
before:
Here is a big block of text with lots of repeating words. All the words are words that are words and more words. A group of donkeys are always words, but a group of words are not always donkeys.
after:
Here is a big block of text with lots of repeating things. All the things are things that are things and more things. A group of donkeys are always things, but a group of things are not always donkeys.