Furthest back in position; the rearmost or most backward of something.
From back (Old English bæc) + -most (superlative suffix from Old English mǽst meaning most), literally 'most back.'
Backmost is a wonderfully old-fashioned word that shows English's flexibility—we prefer saying 'rearmost' or 'furthest back' today, but the -most suffix still survives in 'westmost' and 'topmost.'
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