Anything ingenious is smart and clever, but ingenuous means innocent and naive. The ingenious villain in your favorite comic book series might come up with diabolical plots, while the ingenuous heroine doesn't suspect a thing.
Although the adjective ingenious is more closely related to the noun engine than to the word genius, a genius is likely to have ingenious ideas. Inventing a self-cleaning house ingenious. So is figuring out the math to get a rocket to the moon. Here are some inspiring examples:
Many libraries have found ingenious ways to keep their communities reading. (New York Times)
The division would be associated with lunar orbit rendezvous, one of the most ingenious and elegant solutions to the challenge of propelling extraordinarily heavy objects on the several-hundred-thousand-mile journey to the Moon and back. (Hidden Figures)
Innocently change second the “i” in ingenious to a “u” and you have the word ingenuous. Anything (or anyone) ingenuous is open, sincere, and a little naive. Its opposite is disingenuous, which means “insincere.” Here are some examples:
Now I realize the word “lie” implies knowing intent to mislead, as opposed to possibly ingenuous misstatement of fact. (Washington Post)
Straightforward individuals are frank, sincere, and ingenuous. (Scientific American)
Here’s an ingenious mnemonic to remember the difference between these commonly confused words: ingenious rhymes with genius, while ingenuous sounds more like genuine.