G0552
ἄπειρος
unacquainted
ἄπειρος, -ον (ἀ- neg., πεῖρα, trial), [in LXX: Num.14:23, Zec.11:15 (אֱוִלִי) Jer.2:6 (עֲרָבָה) * ;] without experience of: with genitive of thing(s), Heb.5:13 (MM, VGT, see word).† (AS)
Full Thayer's lexicon entry
ἄπειρος — ápeiros
ἄπειρος, ἀπειρον (πεῖρα trial, experience), inexperienced in, without experience of, with the genitive of the thing (as in Greek writings): Heb 5:13. ((Pindar and Herodotus down.))
1 occurrence