The word "kleis" is spelled with the letters K-L-E-I-S. In IPA phonetic transcription it is spelled /klis/. The /k/ sound is made by closing the back of the throat and pushing air out. The /l/ sound is made by putting the tip of the tongue behind the front teeth and vibrating the voice box. The /i/ sound is made by keeping the tongue high and forward in the mouth while producing a short, sharp sound. Finally, the word ends with the /s/ sound, which is produced by blowing air through a slightly open mouth.
The word "kleis" is of Greek origin. Its etymology can be traced back to the Ancient Greek word "kleís" (κλεῖς) which means "key" or "bolt". This Greek word itself comes from the Proto-Indo-European root "*klī-", which means "to lean" or "to incline". Over time, the Greek word "kleís" evolved to have the specific meaning of a key or a bolt used to secure and lock doors.