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From the metrication of 20/20, where 20 ft is replaced by 6 m in the eye test.
Etymology from Wiktionary, CC BY-SA 4.0.
6/6
Today it means: Synonym of 20/20. Full definition →
Today it means: Synonym of 20/20. Full definition →
From the metrication of 20/20, where 20 ft is replaced by 6 m in the eye test.
Etymology from Wiktionary, CC BY-SA 4.0.