billow
Concise Oxford English Dictionary © 2008 Oxford University Press:
billow/ˈbɪləʊ/
▶noun
- 1 a large undulating mass of cloud, smoke, or steam.
- 2 archaic a large sea wave.
■ (of smoke, cloud, or steam) move or flow outward with an undulating motion.
– derivatives
billowy adjective.
billowy adjective.
– origin C16: from ON bylgja.
'billow' also found in these Oxford entries:

