G0196
ἀκριβέστατος
strictest
ἀκριβής, -ές [in LXX: Dan LXX 2:45 6:12 (יַצִּיב) Dan.4:25, Est.4:5, Sir.18:29 19:25 31:24 32:3 * ;] exact, precise, careful, of things and persons: superl., Act.26:5.† (AS)
Full Thayer's lexicon entry
ἀκριβέστατος — akribéstatos
ἀκριβής, (ές, genitive (οῦς, exact, careful. The neuter comparitive is used adverbially in Act 18:26; Act 23:15; Act 23:20; Act 24:22; ἡ ἀκριβεστάτη αἵρεσις the straitest sect i. e. the most precise and rigorous in interpreting the Mosaic law, and in observing even the more minute precepts of the law and of tradition, Act 26:5. (From Herodotus down.)
1 occurrence