Immutable: adjective

Cambridge Dictionary

"not changing, or unable to be changed"

immutableCambridgeWords

Merriam-Webster

"not capable of or susceptible to change"

Definition of IMMUTABLEMerriamWebster

Mozilla

"An immutable object is one whose content cannot be changed."

Immutable - MDN Web Docs Glossary: Definitions of Web-related terms | MDN