Inflected forms: pl. air·y-fair·ies Chiefly British Slang One that is insubstantial or impractical: They'd wanted him for Ambassador in Paris but he'd turned it down; he'd no patience with the airy-fairies (John le Carré).
ADJECTIVE:
Insubstantial or impractical: You are talking about some airy fairy concept which will never come in my lifetime (Margaret Thatcher, Christian Science Monitor July 29, 1988).