Something natiform resembles or has the form of the buttocks. It
derives from Latin nates, plural of natis, a buttock. Ammon Shea
mentions this word in his book Reading the OED, in which he
records his experience of spending a year scanning the second
edition of the Oxford English Dictionary cover to cover, all
21,730 pages of it. He wrote that he was surprised to learn that
it had never been used as an insult, so refuting the premise of
an entry in Depraved and Insulting English, which he earlier
wrote with Peter Novobatzky. This may be explained easily
enough. The word never moved beyond a limited medical
circulation and so it never gained the instant recognition
necessary for it to be applied insultingly. Also, it has never
been employed to refer to the buttocks themselves, instead
always to some anatomical feature that contains a deep cleft.
The OED marks it as obsolete, though natiform skull, bony
nodules on the surface of the skull in infants with congenital
syphilis (also called Parrot nodes), is in so