A ditch, channel, or water-filled depression; also dialectal for trousers or underclothes (regional).
From Old English 'gōte' (watercourse) or Dutch 'goot' (gutter). The meaning branched into both drainage features and clothing slang in various English dialects.
The word 'gotch' for underwear is particularly common in Canadian and Australian English—it shows how languages develop different slang for the same items in different regions.
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