Table schema:
CREATE TABLE table_name_76 (initial_syllable_open_semi_open_unstressed_vowels VARCHAR)

Question: What is 17th c., when Initial-Syllable Open/Semi-Open Unstressed Vowels is "o /ɵ/"?
SQL: SELECT 17 AS th_c FROM table_name_76 WHERE initial_syllable_open_semi_open_unstressed_vowels = "o /ɵ/"