Archaic or rare verb meaning to double, duplicate, or make twofold.
From 'dupli-' (double) combined with '-fy' (suffix meaning 'to make'), creating 'to make double'. This verb is essentially obsolete, superseded by 'duplicate' and 'double'.
English once had 'duplify,' 'triplify,' 'quadruplify'—systematic verb formations using '-fy.' But speakers preferred 'triple' and 'quadruple' as adjectives instead, and 'duplify' lost the competition for survival!
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