The word hairdressers 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: 15
Highest Scoring Words With Friends™ Play In The Letters
Seven Letter Word Alert: (48 words)
adherer, adheres, dashers, dearies, deashes, derries, desirer, desires, disease, dresser, dresses, erasers, hardier, headers, headier, hearers, hearsed, hearses, heiress, herders, herdess, hissers, raiders, raisers, rashers, readers, readier, readies, rearise, redress, redries, reheard, rehears, rehides, rehired, rehires, rereads, reshare, resider, resides, sassier, seaside, shaders, shadier, sharers, sheared, shearer, sierras