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restroom vs. bathroom

[rest- room, room] / ˈrɛstˌ rum, ˌrʊm /
Or rest room

noun

  1. rooms or a room having a sink, toilet, and other facilities for use by employees, visitors, etc., as in a store, theater, or office.

[bath-room, -room, bahth-] / ˈbæθˌrum, -ˌrʊm, ˈbɑθ- /

noun

  1. a room equipped for taking a bath or shower.

  2. toilet.

idioms

  1. go to / use the bathroom, to use the toilet; urinate or defecate.