lighter-than-air
adjective
light·er-than-air ˈlī-tər-thən-ˈer 
: of less weight than the air displaced
Word History
First Known Use
1901, in the meaning defined above
lighter-than-air
adjective
as in weightless
Synonyms & Similar Words
Relevance
- weightless
- vaporous
- buoyant
- lightweight
- unsubstantial
- diaphanous
- insubstantial
- wispy
- rarefied
- downy
- feathery
- gauzy
- dainty
- pillowy
- gossamer
- flimsy
- ethereal
- cumulous
- tender
- cobwebby
- airy
- fluffy
- delicate
- light
- gauzelike
- gossamery
Antonyms & Near Antonyms
- heavy
- leaden
- substantial
- solid
- weighty
- firm
- ponderous
- bulky
- unwieldy
- burdensome
- cumbersome
- hefty
- lumpish
- hulking