#0196 ἀκριβέστατος [ἀκριβής] akribestatos {ak-ree-bes'-ta-tos}

 superlative of akribes (a derivative of the same as G0206); TDNT - n/a; adj

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

 1) exact, careful
 2) of the strictest sect: the most precise and rigorous in
    interpreting the Mosaic law, and in observing even the more
    minute precepts of the law and tradition

—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 - most straitest 1; 1

—Exhaustive Concordance (KJV Translation Frequency & Location)