'viscous' originates from Latin, specifically the word 'viscosus,' where 'viscum' meant 'mistletoe' or 'birdlime,' a sticky substance.

'viscosus' transformed into the Old French word 'visqueux,' and eventually became the modern English word 'viscous' through Middle English.

Initially, it meant 'sticky or adhesive,' but over time it evolved into its current meaning of 'having a thick, sticky consistency.'