From Wiktionary, the free dictionary
From Latin diuturnitatem.
diuturnity (uncountable)
- (rare, obsolete) Long duration; lastingness.
1658, Sir Thomas Browne, Urne Buriall, Anchor, published 1967, pages 279, 282:What Prince can promise such diuturnity unto his Reliques […] Diuturnity is a dream and folly of expectation
