the GNU version of the Collaborative International Dictionary of English
v. To extent in length; to make longer in extent or duration
verb-intransitive. To become longer.
The Century Dictionary and Cyclopedia
To make long or longer; extend or elongate in space or in duration; protract or prolong: as, to lengthen a line; to lengthen life; to lengthen a vowel or syllable in pronunciation.
To grow long or longer; extend in length.
WordNet 3.0 Copyright 2006 by Princeton University. All rights reserved.
v. become long or longer
v. make longer
Word Usage
"The word Lent, however, comes from the Anglo-Saxon word lengthen, which means: Spring."