How to say “Cool” in Thai
เย็น
yen
“cool / evening”
“Cool” in Thai is เย็น, written yen in the Latin alphabet.
Tone
เย็น carries a mid tone — level, no movement. Thai uses tone to tell words apart, so the pitch is part of the word, not an accent you can drop.
The shortest way in is an English intonation you already use. Say “Yeah.” out loud — bored and flat, your voice at rest and going nowhere — then say เย็น with that same shape.