viscous

adjective

vis·​cous ˈvi-skəs 

1

: having a thick or sticky consistency : viscid

viscous secretions

viscous corn syrup

2

technical : having or characterized by a high resistance to flow

viscous lava

viscously adverb

viscousness noun

Synonyms of viscous

• thick
• sticky

Examples of viscous in a Sentence

viscous syrup that takes forever to pour from a narrow-neck bottle

Recent Examples on the Web

Existing fiber supplements are typically derived from seed husks and roots, and are typically thick, viscous, and bulky. —Shimite Obialo, Forbes.com, 26 May 2026

The soluble fiber in oats, particularly the polysaccharide beta-glucan, forms a viscous gel in the digestive tract. —Lauren Manaker Ms, Health, 22 May 2026

Not only can the viscous substances gunk up the machine, leaving a residue and potentially feeding bacteria, but prolonged exposure to these molecules in the air can have negative effects, according to the American Lung Association. —Terri Williams, Architectural Digest, 16 Apr. 2026

That, the researchers surmise, is driving a general eastward flow of material through the viscous mantle. —ArsTechnica, 10 Apr. 2026

Word History

Etymology

Middle English viscouse, from Anglo-French viscos, from Late Latin viscosus full of birdlime, viscous, from Latin viscum mistletoe, birdlime; akin to Old High German wīhsila cherry, Greek ixos mistletoe

First Known Use

14th century, in the meaning defined at sense 1

Rhymes for viscous

• discus
• hibiscus
• meniscus

Kids Definition

viscous

adjective

vis·​cous ˈvis-kəs 

1

: having the characteristic of stickiness

2

: having or marked by viscosity

Medical Definition

viscous

adjective

vis·​cous ˈvis-kəs 

1

: having a glutinous consistency and the quality of sticking or adhering : viscid

2

: having or characterized by viscosity

a viscous flow