"an ability to interest casual students"
"showed a casual disregard for cold weather"
"an utterly insouciant financial policy"
"an elegantly insouciant manner"
"drove his car with nonchalant abandon"
"was polite in a teasing nonchalant manner"

"a casual remark"
"information collected by casual methods and in their spare time"

"casual clothes"
"everyday clothes"

"seek help from casual passers-by"
"a casual meeting"
"a chance occurrence"

"a casual (or cursory) inspection failed to reveal the house's structural flaws"
"a passing glance"
"perfunctory courtesy"

"casual employment"
"a casual correspondence with a former teacher"
"an occasional worker"

"a broken back is nothing to be casual about; it is no fooling matter"

"using their Christian names in a casual way"
"lectured in a free-and-easy style"

"a difficult feat performed with casual mastery"
"careless grace"