There are many different words that can be used as synonyms for the phrase "without humor". Some of the most common options include "serious", "solemn", "stern", "grave", "earnest", "somber", "dour", "austere", and "unsmiling". Depending on the context in which the phrase is being used, other synonyms might also be appropriate, such as "uncomical", "unfunny", or "devoid of levity". Ultimately, the choice of word will depend largely on the tone and intended meaning of the sentence or passage in which it is used, as well as the specific connotations associated with each individual synonym.