Synonyms for lengthen
verb
To make longer
extend, stretch, reach, elongate, protract, prolongate, prolong, distend, dilate, amplify, draw out, expand, augment, proceed, continue, string out*, let out*; see also increase 1.
Antonyms decrease*, contract, draw in.
To grow longer
produce, increase, expand; see grow 1. See syn. study at extend.
See lengthen in Webster's New World Roget's A-Z Thesaurus II
Learn more about lengthen