analogous
Meaning: similar to, so that an analogy can be drawn
Usage: Though they are unrelated genetically, the bone structure of whales and fish is quite analogous.
atypical
Meaning: not typical, unusual
Usage: Screaming and crying is atypical adult behavior.
archetypal
Meaning: most representative or typical
Usage: Some believe George Washington, with his flowing white hair and commanding stature, was the archetypal politician.