waterhole

• water-hole
• water hole

• water +‎ hole.
• (astronomy): Coined by Bernard Oliver in 1971, in allusion to the idea that this part of the spectrum would be that used by extraterrestrial intelligence to communicate.

waterhole (plural waterholes)

1. A depression in which water collects, especially one where wild animals come to drink.
   • 1907, Barbara Baynton, edited by Sally Krimmer and Alan Lawson, Human Toll (Portable Australian Authors: Barbara Baynton), St Lucia: University of Queensland Press, published 1980, page 268:

     From habit the sheep would head for the river, but, though it was early spring, the winter had been droughty, and the river was only a string of dangerous water-holes.

2. (informal) A watering hole; a place where people meet to drink and talk.
3. (astronomy) A part of the electromagnetic spectrum, between the regions where hydrogen and hydroxyl radiate, that is relatively quiet in terms of radio astronomy.

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