From The Collaborative International Dictionary of English v.0.48 :
Sanctitude \Sanc"ti*tude\, n. [L. sanctitudo.]
Holiness; sacredness; sanctity. [R.] --Milton.
[1913 Webster]
From WordNet (r) 3.0 (2006) :
sanctitude
n 1: the quality of being holy [syn: holiness, sanctity,
sanctitude] [ant: unholiness]