1) to walk with the feet near together
2) to come together, meet with one
3) of things which fall out at the same time, to happen, turn out, come to pass
Part of Speech: verb
From G4862 and the base of G939; to walk (figuratively transpire) together, that is, concur (take place): - be (-fall), happen (unto).
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 συμβαίνω; click on the second column to search for that grammatical form of the root συμβαίνω; click on the third column to search for that word and grammatical form; click on the total to search for the root συμβαίνω.