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to rub; to pat; to stroke; to massage
「擦る」 has other readings with different meanings.
母は子どもの背中をやさしく擦った。
The mother gently stroked the child's back.
冷えた手を擦って温めた。
I rubbed my cold hands to warm them up.
痛む肩をしばらく擦り続けた。
I kept rubbing my sore shoulder for a while.