The word 'casual' means something that is relaxed, not formal, or done without much thought. For example, wearing jeans and a t-shirt is a casual outfit.
You pronounce 'casual' like 'kazh-oo-uhl'.
The word 'casual' comes from the Latin word 'casualis', which means 'happening by chance'.
The word 'casual' in Hindi is 'अनौपचारिक' (Anaupacharik).