Impulsive (4)
'impulsive' is the definition.
(I know that impulsive can be written as rash)
This is the entire clue.
(Other definitions for rash that I've seen before include "Eruption of spots on skin" , "Impetuous; skin ailment" , "Lacking in caution" , "Foolhardy with skin ailment" , "spate" .)
(Other definitions for quixotic that I've seen before include "Unrealistic and impractical" , "Visionary" , "Extravagantly romantic" , "Romantically impractical" , "donnish?" .)
'impulsive' is the definition.
(I know that impulsive can be written as capricious)
This is all the clue.
(Other definitions for capricious that I've seen before include "Changeable in mood" , "Arbitrary and inconsistent" , "on a whim" , "Given to sudden mood swings" .)