Meaning
see IMPOSSIBLE, A, No. 1.
"without strength" (a, negative, sthenos, strength), is translated "impotent" in Act 4:9. See FEEBLE, SICK, WEAK.
"to be without strength" (akin to A, No. 2), is translated "impotent folk" in Joh 5:3, AV; cp. Joh 5:7 (the present participle, lit., "being impotent"). See DISEASED, SICK, WEAK.