Unchanging
Part of speech: adjective
Definition: remaining constantly unchanged
Example sentence: People have known for thousands of years that oil was abundant on Alaska's North Slope, a vast tundra, flat and treeless, on and on and on, from the foothills of the Brooks Mountain Range to the Arctic Ocean, an endless, unchanging landscape bigger than Idaho.
Consistent
Part of speech: adjective
Definition: of a regularly occurring, dependable natureOf a set of statements, such that no contradiction logically follows from them.
Example sentence: Do not listen to the rhetoric from campaigns, but rather, hold everyone of us accountable, hold me accountable and every other candidate accountable to be a consistent conservative.