Unimpregnable Share definition Flag 1. Adj. Looking or seeming sexually challenging or cold but ultimately having or wanting to have sex with you. Ha, I like how you thought I'd never get with Brenda! Didn't you know she was unimpregnable? Unimpregnable by oceanrobot February 28, 2011 0 0 Get merch Get the Unimpregnable mug. Buy Now — $32.95 See more merch