While I understand the word "Genious" as a noun for a smart person, I expected "Ingenious" to be the opposite. However, that is not the case. Can anyone explain as to what "Ingenious" really means, how it is different compared to "Genious", and why it is used that way?

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    The prefix in- doesn't have to mean not. If you google genius definition, Oxford Languages gives an explanation of the development in meaning of the word, and also a link to their definition of ingenious (which has a different Latin derivation). Jan 26 at 9:55
  • geniusvery great and rare natural ability or skill, especially in a particular area such as science or art, or a person who has this ingenious– (of a person) very intelligent and skilful, or (of a thing) skilfully made or planned and involving new ideas and methods
    – Mari-Lou A
    Jan 26 at 19:10

1 Answer 1


The prefix "In" sometimes means "not". For example, "Inglorious" means "not glorious", and "Intransitive" is the opposite of "transitive".

But this is not always the case. for example "inflammable" means much the same as "flammable", abler to be set on fire, and "inflame" means to excite emotion, metaphorically to set on fire. It does not mean to put out a fire. "Indwelling" means "residing within" and has no negative implication. Indeed a prefix "In" can mean "inside" or "inward" in many cases.

Merriam-webster defines "
ingenious" as:

(1) having or showing an unusual aptitude for discovering, inventing, or contriving; an ingenious detective

(2) marked by originality, resourcefulness, and cleverness in conception or execution; an ingenious contraption

This word is not derived from the same Latin root as "genius". Note the difference in spelling.

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