From adunatos; to be unable, i.e. (passively) impossible -- be impossible.
see GREEK adunatos
a. not to have strength, to be weak; always so of persons in classic Greek
b. a thing ἀδυνατεῖ, cannot be done, is impossible; so only in the Sept. and N. T.: οὐκ ἀδυνατήσει παρά τῷ Θεῷ (τοῦ Θεοῦ L marginal reading T Tr WH) πᾶν ῤῆμα, Luke 1:37 (the Sept. Genesis 18:14) (others retain the active sense here: from God no word shall be without power, see παρά, I.
b. cf. Field, Otium Norv. pars iii. at the passage); οὐδέν ἀδυνατήσει ὑμῖν, Matthew 17:20 (Job 42:2).