1) to act as a mediator between litigating or covenanting parties
1a) to accomplish something by interposing between two parties
1b) to mediate
2) act as a sponsor or surety
2a) to pledge one's self, give surety
Part of Speech: verb
Citing in TDNT: 4:598, 585
From G3316; to interpose (as arbiter), that is, (by implication) to ratify (as surety): - confirm.
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 μεσιτεύω; click on the second column to search for that grammatical form of the root μεσιτεύω; click on the third column to search for that word and grammatical form; click on the total to search for the root μεσιτεύω.