The word triangularity 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: 20
Highest Scoring Words With Friends™ Play In The Letters triangularity
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Seven Letter Word Alert: (29 words)
agility, angrily, angular, arraign, gauntly, gauntry, granary, guarani, intagli, lairing, liturgy, lunaria, nattily, natural, railing, rattail, ratting, rutting, tailgun, tailing, tarring, tauting, tilting, titular, trinity, unitary, urinary, utility, yirring