Webster's 1828 Dictionary
BILLOWING
ppr. Swelled into a large waves or surges.
American Oxford Thesaurus
billowing
billowing adjective rolling, swirling, undulating, surging, heaving, billowy, swelling, rippling.
Oxford Thesaurus
billowing
billowing adjective billowing clouds of dust: rolling, swirling, undulating, rising and falling, billowy, swelling, rippling; rare undulant.
The Wordsmith Dictionary