Definify.com
Webster 1913 Edition
Woolgathering
Wool′gathˊer-ing
,Adj.
Indulging in a vagrant or idle exercise of the imagination; roaming upon a fruitless quest; idly fanciful.
Wool′gathˊer-ing
,Noun.
Indulgence in idle imagination; a foolish or useless pursuit or design.
His wits were a
woolgathering
, as they say. Burton.