Not to be altered; immutable: the unchangeable seasons. (adjective)
American Heritage(R) Dictionary of the English Language, Fifth Edition. Copyright (c) 2011 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.
Use "unchangeable" in a sentence
"Elements react under certain unchangeable conditions."
"In the early fervour of his fancy he had assured Mrs. Robinson his love would remain unchangeable till death, and that he would prove unalterable to his Perdita through life."
"There are solitary rock-columns that spring straight up out of the water and dark grottoes with narrow entrances; there are barren, perpendicular precipices, and soft, leaf-clad inclines; there are small points, and small inlets, and small rolling stones that are rattlingly washed up and down with every dashing breaker; there are majestic cliff-arches which project over the water; there are sharp stones that are constantly being sprayed by a white foam; and others that mirror themselves in unchangeable dark-green still water."