Past tense of shower; either bathed in a shower, or received a large amount of something in abundance.
From Old English 'scur' (shower of rain). The term expanded from rain showers to the fixture/action of bathing, and metaphorically to mean receiving abundant amounts of anything.
The modern shower fixture only became common in homes in the 1930s-1950s, yet people used 'shower' as a verb long before—because they already showered in rain and outdoor showers for centuries!
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