1550s, "pertaining to a diameter," from Old French diametral (14c.), from Medieval Latin diametralis, from diametrus (see diameter).
Entries linking to diametral
diameter n.
late 14c., in geometry, "chord of a circle or sphere which passes through its center; the length of a diameter," from Old French diametre, from Latin diametrus, from Greek diametros (gramme) "diagonal of a circle," from dia "across, through" (see dia-) + metron "a measure" (from PIE root *me- (2) "to measure").