from Wiktionary, Creative Commons Attribution/Share-Alike License
- adj. Resembling or having the form of buttocks.
from The Century Dictionary and Cyclopedia
- Like or likened to buttocks, as the umbones of a shell: as, the natiform tubercles of the brain.
First attested in 1681; formed as the Latin natis (“rump”, “buttocks”; from whose plural derives the English nates, “buttocks”, “haunches”) + the English -i- + -form. (Wiktionary)