noun

• (UK, Ireland, Commonwealth) A lavatory: a room used for urination and defecation.
  "I suppose it is unreal because we have been expecting it [sc. World War II] for so long now, and have known that it must be got over before we can go on with our lives. Like in the night when you want to go to the loo and it is miles away down a freezing cold passage and yet you know you have to go down that passage before you can be happy and sleep again."
• (UK, Ireland, Commonwealth) A toilet: a fixture used for urination and defecation.
  "The lack of running water in rural areas often makes Western-style loos hygienic disasters. Suddenly the noncontact squat toilet doesn′t look like such a bad option any more (as long as you roll up your trouser legs)."

verb

• (now dialect, used with at, upon or infinitive) To urge on with cries of loo or (figuratively) by other shouting or outcry.
  "And therefore next uncouple either Hound [sc. George Monck and Prince Rupert], And loo them at two Hares ere one be found."

noun

• (figuratively) Any group of people.

verb

• (transitive) To beat in the card game lanterloo.
  "He was seldom indeed without two good trumps, and therefore almost invariably loo'd those who stood."
• (figurative, now dialect) To pay any penalty to any community.