1) to deposit together with another
2) to deposit one's vote in the urn with another
3) to consent to, vote for, agree with
Part of Speech: verb
Middle voice from G4862 and G2698; to deposit (one's vote or opinion) in company with, that is, (figuratively) to accord with: - consent.
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 συγκατατίθεμαι; click on the second column to search for that grammatical form of the root συγκατατίθεμαι; click on the third column to search for that word and grammatical form; click on the total to search for the root συγκατατίθεμαι.