0 (of clothing) neat and stylish, but not too formal, especially when this is the accepted way of dressing for a particular situation, place, or social occasion:
Audiences usually meet smart casual standards, with some performance companies explicitly telling audiences to wear whatever makes them comfortable.
A jacket, dress shirt, necktie and jeans are demonstrated as "smart casual" attire.
Sokkie dancers in nightclubs mostly wear shoes and dress smart casual.
