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1. Not subject or susceptible to change or variation in form or quality or nature
   "the view of that time was that all species were immutable, created by God";
   - changeless
    
2. Constant and unchanging
   "the immutable laws of nature"
    
3. (programming, of a variable) having a value that cannot be changed after it is initialized

See also: constant

Antonym: changeable

Encyclopedia: Immutable