mid 17th century (in the senses ‘of the same rank’ and ‘place in the same rank’): from co-‘together’ + Latin ordinare (from ordo ‘order’), on the pattern of subordinate
17世紀半ば(「同格の」「同格に置く」という意味で):co'together' + Latin ordinare(ordo 'order' から)、subordinate のパターンで。