Gareth

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Of Old Welsh origin and cognate with the Welsh name Geraint (from Latin Gerontius(“old man”), from Ancient Greek γέρων(gérōn, “old man”)) or perhaps the word gwareddawg, gwaredd(“gentleness”); see gwâr(“gentle”).

Cockney rhyming slang based on the name of actor Gareth Hunt. [1] [2] [3]