One who rains or something that produces rain; more commonly used as a German name meaning 'warrior' or related to rain.
From 'rain' plus '-er' suffix making 'one who rains,' though this is rare. As a name, it comes from Germanic 'Raginar' combining 'ragin' (advice/counsel) and 'arr' (warrior).
While 'rainer' isn't common English, as a German name it's historically connected to Celtic and Germanic warrior traditions—it's one of those words that shows how English borrowed naming conventions from Germanic languages after 1066.
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