IPA: /nɒnˈkæʒuəl/
KK: /nɑnˈkæʒuəl/
Describing something that is formal or not relaxed in style or manner.
The event had a noncasual dress code, requiring guests to wear formal attire.
Noncasual → It is formed from "non-" (meaning not) and "casual" (from Latin "casualis", meaning occurring by chance). The word "noncasual" means not occurring by chance or not informal.
Think of 'not' ('non-') and something that happens 'by chance' ('casual') — that's why noncasual means something that is not informal or random.