unprepossessing
🇺🇸
/ˌʌnˌpriːpəˈzesɪŋ/
🇬🇧
/ˌʌnˌpriːpəˈzesɪŋ/
not looking interesting or attractive
The library was a bit unprepossessing from the outside, but inside it was a treasure trove of books.