FIXITY
immutability, immutableness, fixity
(noun) the quality of being incapable of mutation; “Darwin challenged the fixity of species”
fastness, fixedness, fixity, fixture, secureness
(noun) the quality of being fixed in place as by some firm attachment
Source: WordNet® 3.1
Etymology
Noun
fixity (countable and uncountable, plural fixities)
(uncountable) The state or condition of being fixed.
(countable) Something fixed.
(programming) The position of an operator relative to its operand (prefix, postfix) or operands (infix).
Synonyms
• (state or condition of being fixed): fixedness
Source: Wiktionary
Fix"i*ty, n. Etym: [Cf. F. fixité.]
1. Fixedness; as, fixity of tenure; also, that which is fixed.
2. Coherence of parts. Sir I. Newton.
Source: Webster’s Unabridged Dictionary 1913 Edition