De fato, a Wikipedia se refere a todos eles como princípios:
In software engineering, Don't Repeat Yourself (DRY) or Duplication is Evil (DIE) is a principle of software development
KISS is an acronym for the design principle "Keep it simple, Stupid!".
The principles when applied together intends to make it more likely that a programmer will create a system that is easy to maintain and extend over time