unalterableness

WordReference Random House Learner's Dictionary of American English © 2025

un•al•ter•a•ble /ˌʌnˈɑltərəbəl/  adj. 

1. that cannot be altered:
   an unalterable decision.
un•al•ter•a•bly, adv. 

WordReference Random House Unabridged Dictionary of American English © 2025

un•al•ter•a•ble  (un ôl′tər ə bəl), adj. 

1. not capable of being altered, changed, or modified.

Also, inalterable. 

• un-¹ + alterable 1610–15

un•al′ter•a•ble•ness, un•al′ter•a•bil′i•ty, n. 
un•al′ter•a•bly, adv.