adj. That cannot be precisely defined or put into words
adj. That defies description; indescribable
n. Anything that cannot be defined.
the GNU version of the Collaborative International Dictionary of English
adj. Incapable of being defined or described; inexplicable.
The Century Dictionary and Cyclopedia
Not definable; incapable of being defined or exactly described; not susceptible of definition: as, an indefinable boundary; an indefinable word; indefinable sensations.
WordNet 3.0 Copyright 2006 by Princeton University. All rights reserved.
adj. not capable of being precisely or readily described; not easily put into words
adj. defying expression or description
Word Usage
"Hers was an extreme lithesomeness, and she moved with a certain indefinable airiness, approaching one as down might float or as a bird on noiseless wings."