Antonyms for Thin (opposite meaning)
WordNet sense 1 (relatively dense in consistency):
thick
WordNet sense 2 ((of sound) having marked depth and body):
full
WordNet sense 3 (having much flesh (especially fat)):
fat
WordNet sense 4 (with a thick consistency):
thickly
WordNet sense 5 (make thick or thicker):
thicken
WordNet sense 6 (increase (one's body weight)):
gain
From the ODE community, based on WordNet
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