トイレ

といれ
noun
toilet, bathroom
1. toilet, restroom, bathroom
A room containing a toilet. The most common word for toilet/restroom in modern Japanese.
トイレどこです
Where is the toilet?
I'll go to the restroom for a moment.
May I use the restroom?
すみません、トイレ二階(にかい)あります一階(いっかい)あります
Excuse me, is the restroom on the second floor or the first floor?
My child says they want to go to the restroom, so please let them go right away.

トイレ is the most common and neutral word for toilet/restroom in modern Japanese, from English "toilet."

ALTERNATIVE TERMS:

COMMON EXPRESSIONS:

CULTURAL NOTE:
Japanese toilets (和式(わしき)トイレ) traditionally require squatting. Modern Western-style toilets (洋式(ようしき)トイレ) often have advanced features like 温水(おんすい)シャワー (bidet), 暖房(だんぼう)便座(べんざ) (heated seat), and 音姫(おとひめ) (sound-masking device).