woolgathering

昨日の高校ラグビー決勝も大接戦で良い試合でした。
さて、昨日の問題 "woolgathering" の正解はCです。答えに付いていた例文をメモするのを忘れたので、辞書の説明と例文を引用します。
・Oxford English Dictionary: Indulgence in aimless thought or dreamy imagining; absentmindedness.: he wanted to be free to indulge his woolgathering
・Merriam-Webster: indulgence in idle daydreaming: my woolgathering was abruptly interrupted by a question from the flight attendant
語源が気になるところですが、後者の辞書に次の説明がありました。

Woolgathering once literally referred to the act of gathering loose tufts of wool that had gotten caught on bushes and fences as sheep passed by. Woolgatherers must have seemed to wander aimlessly, gaining little for their efforts, for in the mid-16th century "woolgathering" began to appear in figurative phrases such as "my wits (or my mind) went a-woolgathering" - in other words, "my mind went wandering aimlessly." From there, it wasn't long before the word woolgathering came to suggest the act of indulging in purposeless mind-wandering.