G0421
ἀνεξιχνίαστος
unsearchable
ἀνεξιχνίαστος, -ον (ἀ- neg., ἐξιχνιάζω, to track out; ἴχνος) [in LXX: Job.5:9 9:10 34:24 (חֵקֶר אַיִן)* ;] that cannot be traced out: Rom.11:33, Eph.3:8 (MM, VGT, see word).† (AS)
Full Thayer's lexicon entry
ἀνεξιχνίαστος — anexichníastos
ἀνεξιχνίαστος, ἀνεξιχνίαστον (alpha privative and ἐξιχνιάζω to trace out), that cannot be traced out, that cannot be comprehended (A. V. unsearchable): Rom 11:33; Eph 3:8. (Job 5:9; Job 9:10; (Job 34:24); the Prayer of Manasses 6 (see the Sept., Tdf. edition, Proleg. § xxix.); several times in ecclesiastical writings.)
2 occurrences
Romans (1), Ephesians (1)