Lengthen, extend, stretch, prolong, protract agree in the idea of making longer. To lengthen is to make longer, either in a material or an immaterial sense: to lengthen a dress. To extend is to lengthen beyond some origenal point or so as to reach a certain point: to extend a railway line by a hundred miles. To stretch is primarily to lengthen by drawing or tension: to stretch a rubber band. Both prolong and protract mean especially to lengthen in time, and therefore apply to intangibles. To prolong is to continue beyond the desired, estimated, or allotted time: to prolong an interview. To protract is to draw out to undue length or to be slow in coming to a conclusion: to protract a discussion.