a. 1. Written or printed in black letter; as, a black-letter manuscript or book. [ 1913 Webster ]

2. Given to the study of books in black letter; that is, of old books; out of date. [ 1913 Webster ]

Kemble, a black-letter man! J. Boaden. [ 1913 Webster ]

3. Of or pertaining to the days in the calendar not marked with red letters as saints' days; -- compare red-letter. Hence: Unlucky; inauspicious. [ 1913 Webster ]