adjective
always used before a noun :happening by chance :not planned or expected
[more ~; most ~] :designed for or permitting ordinary dress, behavior, etc. :not formal
Casual days are days (such as casual Fridays) when a company allows workers to dress in casual clothes.
[more ~; most ~]
done without much thought, effort, or concern
not involving a close or serious relationship
having some interest but not a lot :not serious
happening at certain times but not on a regular basis
US