'rabbinical' originates from the noun 'rabbi' (from Hebrew 'rabbī') plus the adjectival suffix '-ical' (from Latin '-icalis' via Old French), forming an adjective meaning 'relating to a rabbi or rabbis'.

'rabbi' entered English from Medieval Latin 'rabbī' (from Hebrew 'רבי' /rabbī/). The English adjective 'rabbinical' developed by adding the suffix '-ical' to 'rabbi' in post-medieval English.

Initially, 'rabbi' meant 'my master' or 'teacher' in Hebrew; over time the derived adjective 'rabbinical' came to mean 'relating to rabbis or rabbinic literature' in English.