toilet, restroom, bathroom (lit., a place to wash one's hands)

Remember it

Hear "oh" + "tea" + "ah" in the word. Picture someone realizing "oh!", a cup of tea, and someone gasping "ah!" turning into a clear scene for "toilet, restroom, bathroom (lit., a place to wash one's hands)"; that little scene ties otearai to "toilet, restroom, bathroom (lit., a place to wash one's hands)".