tertiary

Where does the word "tertiary" come from? It comes from Latin tertiarius, and was adopted directly into English (1650s).

Tertiary’s story begins in Latin: tertiarius meant “of the third rank.” Of the third rank, from tertius (third). It reached English by 1650s as tertiary. Settled as the English word for something third in importance or order. Today, tertiary means third in order, rank, or importance.

1. Stage 1 · Latin · ancient tertiarius "of the third rank", of the third rank, from tertius (third).
2. Stage 2 · English · 1650s tertiary "third in importance, order, or sequence", settled as the English word for something third in importance or order.