adverb
above all; especially; particularly; all the more
Emphasizes that something is especially true or important in a given context; often used to single out a reason, person, or situation.
今日はわけて寒く感じる。
Today feels especially cold.
彼はわけて数学が得意だ。
He is particularly good at math.
Derived from the verb 分ける (わける, 'to divide, separate'), with the て-form used adverbially. The sense of 'especially' developed from the idea of singling something out from a group.