Milan Kundera Novel, the Unbearable __ of Being

This page is the CodyCross answer for the clue below from Top Secret, Group 2084, Puzzle 4 (Gadget Briefcase).

Question is: Milan Kundera Novel, the Unbearable __ of Being

and the answer is: LIGHTNESS

Word Meaning:

LIGHTNESS — (uncountable) the condition of being illuminated

Definitions from Wiktionary.