1. (v. t.) To extent in length; to make longer in extent or duration; as, to lengthen a line or a road; to lengthen life; -- sometimes followed by out.

2. (v. i.) To become longer.

add to aggrandize amplify augment boost broaden build build up continue dawdle drag out draw draw out dwell on elongate enlarge exalt expand extend fatten fill out hike hike up hold increase inflate jack up jump up keep keep alive keep going keep up lengthen out let out linger on maintain maximize parlay perpetuate preserve procrastinate produce prolong prolongate protract pull put up pyramid raise retain spin out strain stretch stretch out string out sustain tauten temporize tense thicken tighten up