PERMANENCY
permanence, permanency
(noun) the property of being able to exist for an indefinite duration
Source: WordNet® 3.1
Noun
permanency (countable and uncountable, plural permanencies)
The state or quality of permanence.
Synonyms
• perdurance, remanence; see also permanence
Source: Wiktionary
Per"ma*nence, Per"ma*nen*cy, n. Etym: [Cf. F. permanence.]
Definition: The quality or state of being permanent; continuance in the
same state or place; duration; fixedness; as, the permanence of
institutions; the permanence of nature.
Source: Webster’s Unabridged Dictionary 1913 Edition