Fairly large or considerable in size, amount, or extent; substantial enough to be significant or noticeable.
From Middle English size meaning 'a regulation, standard' through Old French sise, ultimately from Latin sedere meaning 'to sit' (referring to a court session). The adjective form with -able emerged in the 16th century.
The journey of 'sizeable' from meaning 'according to regulation' to 'impressively large' mirrors how standards often become benchmarks for impressiveness. It's a perfect example of linguistic drift - what starts as a neutral measurement term gradually acquires positive connotations of adequacy and substantial worth.
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