unalterable
Meaning
not capable of being changed or altered.
Structure
Usage
the terms of the contract were declared unalterable by the court.
his unalterable belief in justice guided all his decisions.
the laws of physics are considered unalterable constants.
Etymology
The word 'unalterable' is a Modern English formation built from classical components. The core 'alter' derives from the Latin verb 'alterāre', meaning 'to change', which itself comes from 'alter', meaning 'other'. The negative prefix 'un-', of Old English and ultimately Proto-Germanic origin, was prefixed to the adjective 'alterable'. 'alterable' itself is formed by adding the suffix '-able', from Latin '-ābilis' via Old French, which denotes capability. Thus, the literal construction "not capable of being changed" maps directly and logically to its modern abstract meaning of permanence or immutability.
Analysis
un: a prefix of germanic origin (old english) meaning "not". alter: a root of latin origin (alterāre) meaning "to change". able: a suffix of latin origin (via old french) meaning "capable of, fit for".