Flaccid : (of part of the body) soft and hanging loosely or limply, especially so as to look or feel unpleasant.Upright : (of a person) sitting or standing with the back straight.Taut : stretched or pulled tight; not slack.Uneven : not level or smooth.Tough : (of a substance or object) strong enough to withstand adverse conditions or rough handling.Antonym of Flaccid is Taut