The phrase "soft in the head" is a derogatory term used to describe someone who is perceived as foolish or lacking intelligence. There are several synonyms that can be used instead of this offensive phrase. One option is to use "simple-minded," which suggests that someone has a childlike innocence and naivety. Another synonym could be "unintelligent," which describes someone who lacks the ability to comprehend complex ideas. Alternatively, "gullible" could be an appropriate term when referring to someone who easily believes things without questioning or investigating. Using these synonyms instead of "soft in the head" is a more respectful and appropriate way to describe someone's intelligence.