imposure comes from Latin impositus, past participle of imponere ('to place upon, impose'), from in- ('on, upon') + ponere ('to place'). An archaic variant of imposture. Morphologically, the prefixed shape matters: the initial element belongs to the recorded formation and helps explain the modern form's surface analysis. In present English, the noun sense is "an act of imposition or deception; a fraud or imposture", so the historical development ends in a clearly identifiable modern dictionary use. The same base also appears in related forms such as impose, imposture, impostor, and imposition. Its semantic neighborhood includes imposture, fraud, deception, and imposition, which helps locate the modern sense without adding a separate etymological claim. The named historical forms include Latin imponere and Latin ponere.