From the Roman calendar month Junius, probably named for the goddess Juno.

Junius (June) was originally the fourth month of an ancient Latin calendar. Plutarch said the month's name was "so called from Juno; some, however, derive them from the two ages, old and young, majores being their name for older, and juniores for younger men." Juno is the principle goddess of the Roman Pantheon. She is the goddess of marriage and the well-being of women. She is the wife and sister of Jupiter. She is identified with the Greek goddess Hera.