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.
(..) All right, so you get it. I'd never even seen back bay. So what happened on that first visit, Joe? Well, he was very nice at first, very funny, very casual. And I think he could tell I was gay, so he showed me this mobile he had, like over a baby's crib. Mm-hmm. (..)2015 Spotlight