1) to make long, to lengthen
2) in the Bible twice of plants, to cause to grow, increase
Part of Speech: verb
From G3372; to lengthen, that is, (middle voice) to enlarge: - grow up.
These two sites give similar information, with the definition from several dictionaries and statistics on the use of the word.
Perseus Digital Library
University of Chicago's Logion lexicon
Thayer's dictionary plus other information.
From this site's dictionary (in Italian)
Click on the first column to search for that word as a form of the root μηκύνομαι; click on the second column to search for that grammatical form of the root μηκύνομαι; click on the third column to search for that word and grammatical form; click on the total to search for the root μηκύνομαι.