billow
UK[ˈbɪləʊ]US[ˈbɪloʊ]
v
(of smoke, cloud, or steam) to move or flow outward in a large, rolling mass
n
a large, rolling mass of cloud, smoke, or steam
Etymology
the word 'billow' entered english in the mid-16th century, likely borrowed from old norse bylgja, meaning 'a wave'. this norse term is related to the old english bylgan, meaning 'to swell, rage', both deriving from the proto-germanic bulgjan, which is linked to the idea of swelling or puffing up. the core semantic thread from its germanic origins connects the concept of a swelling motion to the modern visual of a large, rolling mass, whether of water, smoke, or cloud. its journey reflects a specialization from a general term for a swelling wave to its predominant use describing undulating, cloud-like formations.
Analysis
this word is a simplex form. it is not productively formed from separable morphemes in modern english.
Examples
thick smoke began to billow from the factory's chimneys.
the sails billowed in the strong ocean wind.
a great billow of dust rose from the collapsed building.