viscous

adj. sticky and thick, adhesive; having a high viscosity (Physics)

Viscosity is a measure of the  resistance of a fluid to deform under either shear stress or extensional stress. It is commonly perceived as "thickness", or resistance to flow. Viscosity describes a fluid's internal resistance to flow and may be thought of as a measure of fluid friction. Thus, water is "thin", having a lower viscosity, while vegetable oil is "thick" having a higher viscosity. All real fluids (except superfluids) have some resistance to stress, but a fluid which has no resistance to shear stress is known as an ideal fluid or inviscid fluid. The study of viscosity is known as rheology.
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Adjective
1. having a relatively high resistance to flow
(synonym) syrupy
(similar) thick
2. having the properties of glue
(synonym) gluey, glutinous, gummy, mucilaginous, pasty, sticky, viscid
(similar) adhesive

(a.)
Adhesive or sticky, and having a ropy or glutinous consistency; viscid; glutinous; clammy; tenacious; as, a viscous juice.
  

Synonyms and related words:
adhesive, amylaceous, broad-bodied, bulky, bullnecked, clabbered, clammy, close, close-knit, close-textured, close-woven, clotted, coagulated, coarse, compact, compacted, compressed, concentrated, concrete, condensed, congested, consolidated, corpulent, crammed, crammed full, crass, crowded, curdled, dense, doughy, fat, firm, full, full-bodied, gaumy, gelatinous, glairy, gluelike, gluey, glutenous, glutinose, glutinous, gooey, gross, grumous, gumbo, gumbolike, gumlike, gummous, gummy, hard, heavy, heavyset, impenetrable, impermeable, inspissated, jam-packed, jammed, jelled, jellied, jellylike, massive, mucilaginous, nonporous, packed, pasty, ropy, semifluid, serried, slab, slabby, slimy, slithery, solid, starchy, sticky, stiff, stodgy, stringy, substantial, syrupy, tacky, tenacious, thick, thick-bodied, thick-growing, thickened, thickset, three-dimensional, tough, tremelloid, tremellose, viscid, viscose