The Greek verb adunateo (ἀδυνατέω) means to be impossible, to be unable, or to be powerless. It is derived from adunatos (G102, impossible/unable), itself from the alpha-privative and dunatos (G1415, possible/powerful).
Adunateo appears in one of the New Testament's most faith-defining declarations. When the disciples asked Jesus why they could not cast out a demon, he responded: 'Because you have so little faith. Truly I tell you, if you have faith as small as a mustard seed... nothing will be impossible (adunatsei) for you' (Matthew 17:20). The angel Gabriel echoes this in Luke 1:37: 'For nothing will be impossible (adunatsei) with God.' What is humanly impossible becomes possible through divine power activated by faith.