While it's not a common suffix like "-ing" or "-ly", it is used in some words to indicate a lack of something or a falsehood.
Here are some examples:
* Untruthful: "un-" is a prefix meaning "not," and "-ful" is a suffix indicating "full of" or "characterized by." So, "untruthful" means "not truthful."
* Unfaithful: Similar to "untruthful," "un-" negates the word "faithful," which means "loyal or trustworthy."
* Counterfeit: This word means "fake or imitation," and "counter-" indicates opposition or replacement.
It's worth noting that "false" itself is not a suffix. It's the root word, and other suffixes can be added to it to create new words, like "-hood" in "falsehood."