The word "severi" refers to something that is strict, stern, or harsh. Therefore, some synonyms you could use to describe this type of personality or behavior might include austere, rigid, inflexible, uncompromising, or unyielding. Other words that could be used to convey a similar tone or feeling might include grim, dour, bleak, or forbidding. Depending on the context in which the word is being used, other options may also be appropriate, such as strict, stern, or militant. Regardless of which synonym you choose, however, it is important to consider the nuance of the word and how it relates to the overall meaning of the sentence or phrase in which it is used.