Where does “septuagesimus” come from?
septuagesimus (Latin) comes from Latin septuāgintā, from Latin septmāginta, from Proto-Indo-European septm̥̄ḱomt, from Proto-Indo-European septḿ̥-dḱomt — seven-ten.
septuagesimus (Latin): seventieth
Ancestry of “septuagesimus”, step by step