What rhymes with nightmare - 1 syllable
 airfare
 armchair
 bakeware
 childcare
 cookware
 corsair
 daycare
 delftware
 elsewhere
 fanfare
 flatware
 footwear
 forebear
 giftware
 glassware
 groupware
 hardware
 healthcare
 knitwear
 longhair
 mohair
 neckwear
 nowhere
 nowhere
 shareware
 shorthair
 sleepwear
 software
 software
 somewhere
 somewhere
 sportswear
 stoneware
 swimwear
 threadbare
 timeshare
 warfare
 welfare
 wheelchair
 workfare

What rhymes with nightmare - 2 syllables
 anywhere
 anywhere
 dinnerware
 earthenware
 everywhere
 everywhere
 kitchenware
 outerwear
 panda
 bear
 silverware
 tableware
 thoroughfare
 underwear
 vaporware
 zillionaire

What rhymes with nightmare - 3 syllables
 posterior

What rhymes with nightmare - 4 syllables
 extraordinaire