The Collaborative International Dictionary
Sickerness
Sickerness \Sick"er*ness\, Sikerness \Sik"er*ness\, n.
The quality or state of being sicker, or certain. [Obs.]
--Chaucer. Spenser.
Wiktionary
sickerness
n. 1 (context obsolete English) the state, condition, or quality of being certain; certainty; assurance. 2 (lb en archaic) security; safety; freedom from danger.