Meaning of "casual" in Essential American English Dictionary

casual

adjective us /ˈkæʒ·u·əl/

B1 Casual clothes are comfortable and not formal.

not planned:

a casual remark

relaxed and not seeming very interested in someone or something:

a casual manner
casually adverb

She was dressed casually in shorts and a T-shirt.

(Definition of “casual” from the Webster's Essential Mini Dictionary © Cambridge University Press)