From The Collaborative International Dictionary of English v.0.48:
Fundament \Fun"da*ment\, n. [OE. fundament, fundement,
fondement, OF. fundement, fondement, F. fondement, fr. L.
fundamentum foundation, fr. fundare to lay the bottom, to
found, fr. fundus bottom. See Fund.]
1. Foundation. [Obs.] --Chaucer.
[1913 Webster]
2. The part of the body on which one sits; the buttocks;
specifically (Anat.), the anus. --Hume.
[1913 Webster]