We very often use the word ที่ (thîi) with the meaning "that which" or "that."
We place it after the noun and before the phrase we use to describe the noun.
➤ "the person who is wearing a red hat"
➤ "that food is delicious"
In a similar way, we also use ที่ (thîi) to construct ordinal numbers. Simply place the number after ที่ (thîi).
<<คนที่ใส่ (khon thîi sài)<<
<<…คนนั้น (…khon nán)<<
<<ภึงบ้านแล้ว (thǔeng bâan láaeo)<<
<<หลังไหน (lǎng nǎi)<<