Ingenious/Ingenuous. As similar as they are, they are virtually antonyms. Ingenious means “clever, skillful, or inventive”; while ingenuous means “artless, simple, or innocent”. And while the adjective ingenuity would appear from its spelling to relate to ingenuous, it does not; it’s much closer in its meaning to ingenious.
Aliquot/Aliquant. Wonderful terms with a precise meaning. Aliquot means “a number is contained in a larger whole an exact number of times”. Four is an aliquot part of 16. Aliquant is the opposite and means “a number contained in a larger number, but not in an exact number of times”. Four is an aliquant part of 15.
Flout/Flaunt. Again, these terms are often treated as synonymous, but their meanings are very different. To flout something is “to contravene, disregard, or treat with contempt”. “By walking into the forbidden zone, he flouted the regulation at great risk.” To flaunt is “to show off in an ostentatious manner”. “She flaunted her wealth ostentatiously by wearing twice the jewelry required for the occasion.”
– Ken Butera