Homogeneous vs. homogenous

Watch out: if you ever find yourself writing homogenous, you probably mean homogeneous.

According to the New Oxford American Dictionary:

Homogeneous: “of the same kind, alike … consisting of parts all of the same kind.”

Homogenous: “an old fashioned term for homologous,” which means “having the same relation, relative position, or structure.”

This is one of those distinctions you never notice until you become an editor.