Etymology 1

• French lieu, place
• A particular brand of early toilet cisterns, trademarked 'Waterloo'.
• (fancifully) the exclamation "gare à l'eau!" ("mind the water!") used when emptying a chamber pot out of a window onto the public sidewalk or street.
• the numbering of 00 on a toilet in a building

Etymology 3

Noun

1. A hot, dusty wind in Bihar and the Punjab.
   • 1888, Rudyard Kipling, ‘The Man Who Would be King’, The Phantom ’Rickshaw and Other Tales, Folio Society 2005, p. 135:

     It was a pitchy black night, as stifling as a June night can be, and the loo, the red-hot wind from the westward, was booming among the tinder-dry trees and pretending that the rain was on its heels.