The word nightmarish is playable in Words With Friends™, no blanks required. Because it is longer than 7 letters, you would have to play off an existing word or do it in several moves.
Words With Friends™ Letter Score: 21
Highest Scoring Words With Friends™ Play In The Letters nightmarish
:
Seven Letter Word Alert: (25 words)
airings, animist, arising, garnish, gastrin, harming, hashing, insight, margins, martini, martins, mashing, matings, migrant, misting, raising, ratings, shaming, sharing, smiting, staring, tarnish, thiamin, tigrish, timings