1) to set or bring together
1a) in a hostile sense, of combatants
2) to put (as it were) the perception with the thing perceived
2a) to set or join together in the mind
2a1) i.e. to understand: the man of understanding
2a2) idiom for: a good and upright man (having the knowledge of those things which pertain to salvation)
Part of Speech: verb
Citing in TDNT: 7:888, 1119
From G4862 and ἵημι hiêmi (to send); to put together, that is, (mentally) to comprehend; by implication to act piously: - consider, understand, be wise.
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 σύνιημι; click on the second column to search for that grammatical form of the root σύνιημι; click on the third column to search for that word and grammatical form; click on the total to search for the root σύνιημι.