They are only 'casual' acquaintances. [=they know each other but not very well]
She takes a 'casual' [='nonchalant'] approach to her homework.
He was dressed 'casually' in jeans and a sweatshirt.
(..) And he looks like a snitch on Miami Vice. Would it kill him to wear a tie? I mean, is every day in Iran casual Friday? Where is the Head of my Nuclear Program and Procurer of Women? Where is Nuclear Nadal? You had Nadal executed, Supreme Leader. (..)2012 The Dictator