borrowed from Latin prōtractus, past participle of prōtrahere "to drag forward, draw or pull out, bring into the open, prolong, defer," from prō-, prefix denoting forward movement + trahere "to drag, draw, take along"
extendlengthenprolongprotract mean to draw out or add to so as to increase in length. extend and lengthen imply a drawing out in space or time but extend may also imply increase in width, scope, area, or range. prolong suggests chiefly increase in duration especially beyond usual limits.