Longman Dictionary of Contemporary English
water butt
noun
EXAMPLES FROM CORPUS
▪ After I fell in the water butt.
▪ He always used to tuck it underneath the water butt.
▪ Her next move was towards the water butt.
▪ The water butt juggles with raindrops.
▪ Then there's a water butt up by the back door; and some honeysuckle growing over the porch.
▪ They say there are schemes available that could be implemented, such as the simple water butt.
▪ With a water butt, the water is collected and can be used for gardens.
The Collaborative International Dictionary
Water butt
Water butt \Wa"ter butt`\
A large, open-headed cask, set up on end, to contain water.
--Dickens.
Wiktionary
water butt
n. An open-ended barrel used to contain rainwater; a rain barrel
WordNet
water butt
n. a butt set on end to contain water especially to store rainwater