The word "unalterative" refers to something that cannot be changed or modified. Some synonyms for unalterative include fixed, unchanging, immutable, invariable, permanent, constant, steadfast, and rigid. These words all describe things that remain the same without any possibility of alteration. Furthermore, they all suggest rigidity and lack of flexibility. For instance, one can describe a person with fixed ideas as being unalterative. Similarly, a rule that cannot be changed or modified may be described as immutable. In conclusion, the synonyms for unalterative can be useful when describing things that are resistant to change or modification.