The word blacktopping 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: 32
Highest Scoring Words With Friends™ Play In The Letters blacktopping
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Seven Letter Word Alert: (39 words)
agitpop, appoint, backing, backlit, backlog, backlot, balking, boating, bolting, bopping, botanic, cabling, capitol, capping, caption, coaking, coalbin, coaling, coalpit, coating, copping, gablock, inkblot, lacking, lapping, locking, lockpin, lopping, optical, packing, placing, plating, tabling, tacking, taglock, talking, tapping, topical, topping