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

Lithium batteries struggle in temperatures lower than 32 °F (0 °C) because the reaction that enables them to deliver power slows down, the electrolyte becomes more viscous and increases internal resistance, and this leads to a drop in voltage. —Abhimanyu Ghoshal, New Atlas, 3 Dec. 2025

These are whipped into a viscous, hydrating serum that my skin drinks up in seconds. —Emily Orofino, Vogue, 19 Nov. 2025

Most soluble, or viscous, fiber can absorb water and create a gel in the gut that can lead to slower gastric emptying, reduce blood sugar spikes and potentially lower cholesterol levels, according to Attia. —Angelica Stabile, FOXNews.com, 15 Nov. 2025

Small, viscous waves lapped against the shore, the swell leaving behind a brown shelf of decaying organic matter. —David Wingrave, Harpers Magazine, 24 Oct. 2025

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
• viscus
• 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