General Synonyms:
* Simple: This emphasizes the lack of ornament or excess.
* Plain: Similar to simple, it implies a lack of decoration.
* Severe: This emphasizes the harshness or strictness of something.
* Spartan: This references the simple, disciplined life of the ancient Spartans.
* Unpretentious: This suggests a lack of showy display or pretense.
* Strict: Focuses on the discipline and rigidity of the thing.
More specific synonyms:
* Ascetic: This refers to a lifestyle of self-denial and austerity.
* Uncompromising: Emphasizes the firmness and lack of flexibility in the thing.
* Solemn: This suggests a serious and somber quality.
* Bare: Focuses on the lack of embellishment or adornment.
* Stark: This emphasizes the starkness and bleakness of something.
* Frugal: This refers to the economical and restrained use of resources.
The best synonym for "austere" will depend on the specific context and the nuances you want to convey.