mutable

Etymology

From Middle English mutable, from Old French mutable, from Latin mutabilis (“liable to change”); mutate + -able.

adj

1. Changeable, dynamic, evolutive; inclined to change, evolve, mutate.
   Vndoughtedly constaunce is an honourable vertue, as inconstance is reprochefull and odious. Wherfore that man whiche is mutable for euerye occasyon, muste nedes often repente hym, and in moche repentance is nat only moche foly, but also great detriment: whiche euery wyse man wyll eschue if he can. 1531, Thomas Elyot, “Of Constance or Stabilitie”, in The boke named the gouernour, book III, page e4v
   It is in vain to interpose the explanation that the sonship was mutable. The Broad School do not say so ; and in so far they are consistent, for they recognise no power to produce the mutation. 1864, Rob S. Candlish, “The Fatherhood of God”, in The British and Foreign Evangelical Review, volume XIV, London: James Nisbet & Co., published 1865, page 748
2. (programming, of a variable) Having a value that is changeable during program execution.
   A value of a mutable type can change. Objects and arrays are mutable: a JavaScript program can change the values of object properties and array elements. Numbers, booleans, null, and undefined are immutable. 2011, David Flanagan, JavaScript: The Definitive Guide
3. (astrology) Being one of the signs Gemini, Virgo, Sagittarius and Pisces, associated with adaptability, flexibility and sympathy.

noun

1. Something mutable; a variable or value that can change.
   Hypothesis 6.14: Entropy levels within the social group may vary but must be maintained below maximum entropy on certain relevant variables (e.g., on the six globals and five mutables). 1990, Kenneth D. Bailey, Social Entropy Theory, page 281