IPA: //ˈvɪskəsnəs//
KK: /ˈvɪskəsnəs/
The quality of being thick and sticky, which affects how easily a liquid flows.
The viscousness of the syrup made it difficult to pour.
Viscousness is formed from "viscus" (from Latin, meaning viscera or internal organs, which are often thick and sticky) and the suffix "-ness" (meaning the state or quality of). The word describes the quality of being thick, sticky, or adhesive, similar to the texture of certain bodily fluids.
Think of 'viscus' which relates to thick and sticky internal substances, and remember that 'viscousness' refers to the quality of being thick or sticky.