Thayer's Greek Lexicon

 1. to lead
  1) to go before
  2) to be a leader
1b1. to rule, command
1b2. to have authority over
1b3. a prince, of regal power, governor, viceroy, chief, leading
as respects influence, controlling in counsel, overseers or
leaders of the churches
1b4. used of any kind of leader, chief, commander
1b5. the leader in speech, chief, spokesman
2. to consider, deem, account, think

For Synonyms see entry G5837