The Indonesian word "santai" translates as "serene". It can be used to describe a mental or physical state. For example, if someone is feeling very calm and relaxed, they can say "saya merasa santai", which means "I feel calm". Similarly, if someone is sitting in a comfortable chair with their legs up, they might say "saya sedang santai", which means "I am relaxed". The word 'santai' is often used in casual conversation in Indonesia and is an important part of the Indonesian language and culture.