mightless
Mightless (adj) means Without strength or energy; feeble.
Etymology
Comes from Middle English mightles, from Old English mihtlēas, mihtelēas, from Proto-Germanic *mahtilausaz; equivalent to might plus -less. It is cognate with Scots michtles, Saterland Frisian machtloos, West Frisian machteleas, Dutch machteloos, German Low German machtlos, German machtlos, Swedish maktlös and Icelandic máttlaus.