1An adverb marking that, while doing one thing, the speaker takes the opportunity to also do something else at the same time — often used as 「〜のついでに」.
買い物のついでに、クリーニング店にも寄った。
While out shopping, I also stopped by the dry cleaner's.
出張のついでに、昔の友人に会ってきた。
While on a business trip, I took the chance to meet an old friend.
犬の散歩のついでに、コンビニでゴミを捨ててきた。
While walking the dog, I threw out the trash at the convenience store on the way.
ついでと言っては何ですが、これも一緒に持って行ってもらえますか。
This might be asking too much, but could you take this along too while you're at it?