A nonquest is a (normally sexual)
conquest that never actually happened. Often referred to in the past
tense, once you have entered the 'friendzone' with a person you
thought you might have had a chance of sleeping with.
'I
wish I'd slept with her whilst I had a chance - she's my greatest nonquest'
Man 1: You remember that
girl that used to barmaid at the Ships Head?
Man 2:
Yeah, she was fit - didn't you get it on with her?
Man 1: No, she was one of my nonquests.