Why is the ninth month called September?
1540s, from Middle French rudiment (16c.) or directly from Latin rudimentum "early training, first experience, beginning, first principle," from rudis "unlearned, untrained" (see rude). Related: Rudiments.
rudiment ru·di·ment (rōō'də-mənt)
An imperfectly or incompletely developed organ or part.
Something in an incipient or undeveloped form. Often used in the plural.