c.1400, "withdrawal, removal," from L.L.
subtractionem (nom.
subtractio) "a drawing back, taking away," from L.
subtractus, pp. of
subtrahere "take away, draw off," from
sub "from under" +
trahere "to pull, draw" (see
tract (1)). The mathematical sense is attested from c.1425. The verb
subtract is first recorded c.1540.
"Þou most know þat subtraccion is drawynge of one nowmber oute of anoþer nomber." ["The Crafte of Nombrynge," c.1425]