Synonyms: stable, static, unchanging
Definition: showing little if any change
Usage: a static population
Similar words: unchangeable
Definition: not changeable or subject to change
Usage: a fixed and unchangeable part of the germ plasm-Ashley Montagu; the unchangeable seasons; one of the unchangeable facts of life
Synonyms: unchanging
Definition: conforming to the same principles or course of action over time
Similar words: consistent
Definition: (sometimes followed by `with') in agreement or consistent or reliable
Usage: testimony consistent with the known facts; I have decided that the course of conduct which I am following is consistent with my sense of responsibility as president in time of war- FDR