Antithetical

Adjective

Definition: Directly opposed or contrasted; mutually incompatible.

Definition: Pertaining to or marked by antithesis.

Synonyms: Contradictory, Opposing, Contrary

Antonyms: Similar, Complementary, Harmonious

Examples:

His actions are antithetical to his beliefs.
The two theories are antithetical to each other.

Mnemonics:

Think of "anti" as against or opposing, and "thetical" as related to thesis or a proposition.

Etymology:

Origin:

Derived from the Greek word "antitithenai" meaning "to oppose"

Historical Usage:

The word has been used since the mid-16th century to describe things in direct opposition to each other.

Related Idioms:

Idiom:

"Antithesis of"

Explanation:

Describing something as the complete opposite or contrasting form of something else.

Misconceptions:

Misconception:

Confusing "antithetical" with "antithesis".

Explanation:

While "antithesis" refers to a contrast or opposition between two things, "antithetical" describes something as being directly opposed or contradictory.