Unprepossessingly refers to something that lacks charm or attractiveness. Some synonyms for unprepossessingly are unappealing, uninviting, bland, dull, unassuming, unimpressive, and unremarkable. These words convey a sense of mediocrity or plainness, suggesting a lack of any remarkable or noteworthy qualities. Alternatively, the words unattractive, unsightly, and unfashionable point towards something that is not physically pleasing. These synonyms are useful when describing objects, places, or people who lack charm or attractiveness. In summary, any of these synonyms for unprepossessingly could be used to describe something that is plain, charmless, average, or unattractive.