The flighty purpose never is o'ertook, Unless the
deed go with it. --Shak.
2. Indulging in flights, or wild and unrestrained sallies, of
imagination, humor, caprice, etc.; given to disordered
fancies and extravagant conduct; volatile; giddy;
eccentric; slighty delirious.
Proofs of my flighty and paradoxical turn of mind.
--Coleridge.
A harsh disciplinarian and a flighty enthusiast.
--J. S.
Harford.