ultracasual
/ˌʌltrəˈkæʒuəl/
adjective
- Extremely casual; very relaxed, informal, or unconcerned.
- The dress code for the party was ultracasual, so everyone wore jeans and T-shirts.
- They had an ultracasual conversation over coffee, not discussing anything serious.
- His ultracasual attitude toward deadlines sometimes frustrates his coworkers.