The Collaborative International Dictionary
Diurnation
Diurnation \Di`ur*na"tion\, n.
Continuance during the day. [Obs.]
(Zo["o]l.) The condition of sleeping or becoming dormant by day, as is the case of the bats.
Wiktionary
diurnation
n. 1 (context zoology English) The condition of sleeping or becoming dormant by day. 2 (context obsolete English) continuance during the day