Dutch word spleet comes from Proto-Indo-European *(s)pley-, and later Proto-Germanic *splītaną (To split.)

Detailed word origin of spleet

Dictionary entry	Language	Definition
*(s)pley-	Proto-Indo-European (ine-pro)
*splītaną	Proto-Germanic (gem-pro)	To split.
*splītan	Old Dutch (odt)
splītan	Old Dutch (odt)
spliten	Middle Dutch (dum)	To split.
splijten	Dutch (nld)	To split.
spleet	Dutch (nld)	(childish, especially, in, _, the, _, diminutive) vagina. (vulgar) anus. Crack, cleft, split. Fissure, slit.