A rare or obsolete verb meaning to mark with the south wind or to expose to southerly winds.
Archaic formation with 'be-' prefix plus 'south' (the southern direction or south wind). This appears to be a very rare literary or specialized usage, possibly nautical, with 'be-' creating a causative verb from a directional noun.
Obsolete words like 'besouth' remind us that speakers constantly experimented with the productive 'be-' prefix—most experiments failed, but understanding why some survived (besmear, besiege) and others vanished is a window into what sounds natural to language communities.
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