Synonyms for Viscous (same or very similar meaning)
WordNet sense 1 (having a relatively high resistance to flow):
syrupy
WordNet sense 2 (relatively dense in consistency):
thick
WordNet sense 3 (having the sticky properties of an adhesive):
gluey, glutinous, gummy, mucilaginous, pasty, sticky, viscid, pasty
From the ODE community, based on WordNet
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