Thayer's Greek Lexicon

 1. to set or bring together
  1) in a hostile sense, of combatants
2. to put (as it were) the perception with the thing perceived
  1) 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)

For Synonyms see entry G5825