#4104 πιστόω pistoo {pis-to'-o}

 from G4103; TDNT - 6:174,849; v

—Greek Word Study (Transliteration-Pronunciation Etymology & Grammar)

 1) to make faithful, render trustworthy
    1a) to make firm, establish
 2) to be firmly persuaded of
    2a) to be assured of

—Thayer's (New Testament Greek-English Lexicon)

—Strong's (Greek Dictionary of the New Testament)

—NAS Exhaustive Concordance of the Bible with Hebrew-Aramaic and Greek Dictionaries

 AV - be assured of 1; 1

—Exhaustive Concordance (KJV Translation Frequency & Location)