What does 背筋 mean?
背筋 is a Japanese noun meaning “spine; line of the backbone” in English. It can also be translated as “seam down the back (of clothing)” depending on context. It is written as 背筋 in kanji, せすじ in hiragana, and sesuji in romaji. This word is part of JLPT N3 vocabulary.
Example sentence
それを見てうれしくて背筋がぞくぞくした。
The sight sent chills of delight up my spine.