Unaccustomed to, which means not familiar with, can be replaced with several other synonyms that carry the same meaning. One synonym for the phrase is unfamiliar with, which means lacking knowledge or experience of something. Another alternative is the term inexperienced in, which indicates a lack of skill or practice in a particular activity. Not used to is another phrase that can substitute for unaccustomed to, which suggests a lack of habituation or exposure to something. Similarly, unacquainted with can also be used synonymously which denotes a lack of knowledge or familiarity with someone or something. Regardless of which synonym is chosen, it conveys the same sense of unfamiliarity and lack of experience.