The term O.T. BOOK refers to books in the Old Testament of the Bible. The crossword solutions for this term include Deut (4 letters), Isaiah (6 letters), Ezek (4 letters), Obad (4 letters), GEN (3 letters), Daniel (6 letters), Lev (3 letters), Exod (4 letters), Chr (3 letters), Ezr (3 letters), Hab (3 letters), Hos (3 letters), Isa (3 letters), Jer (3 letters), LAM (3 letters), Mic (3 letters), Neh (3 letters), Num (3 letters), Psa (3 letters), Eccl (4 letters), Esth (4 letters), Ezra (4 letters), RUTH (4 letters), Saml (4 letters), Chron (5 letters), Hosea (5 letters), Kings (5 letters), Nahum (5 letters), Esther (6 letters), Haggai (6 letters), Psalms (6 letters), and Obadiah (7 letters). These books are part of the Hebrew Bible, which is also known as the Tanakh, and they are considered sacred texts by Jews and Christians alike.