Ingenious vs. Ingenuous Are you ready, Grammar Genius? Both ingenious and ingenuous are adjectives. Ingenious indicates cleverness or intelligence, while ingenuous refers to sincerity or a naive nature. How To Use Ingenious When you say ingenious out loud, it sounds like a combination of the words in and genius. Since a genius is an intelligent person, you can use that part of the word to associate ingenious with intelligence. You can use the word to describe things you think are really smart ideas, like “What an ingenious design!” It’s also great for describing smart people: “She’s an ingenious designer.” How To Use Ingenuous Ingenuous is a little trickier, but its pronunciation can still help you determine its meaning. While genuous isn’t actually a word on its own, it sounds very similar to genuine. Genuine, like ingenuous, refers to sincerity or authenticity. While ingenious is fairly common, ingenuous isn’t used as much in writing or speech these days. You can use it to mean sincere, candid, or free from reserve. It’s also another way of saying naive or unsophisticated. The Difference Between Genius and Ingenious Despite both relating to intelligence, genius and ingenious aren’t interchangeable. Genius refers to a high level of intelligence, while ingenious refers to being clever or inventive. Another key difference is that genius is a noun, while ingenious is an adjective. One source of confusion is the prefix in-, which often negates the word it precedes. For example, the word incapable means not capable. In that case, shouldn’t ingenious mean not genius? Not necessarily. The Latin prefixes un- (not) and en-(toward or within) have different meanings. English uses both of these, plus the prefix in- which can be a substitute for either one.Ingeniousness is a characteristic of genius, so those considered geniuses are also ingenious. However, ingeniousness alone isn’t evidence of genius.