noun
folding knife; pocket knife
A knife with a blade that folds into the handle. Common types include penknives and clasp-knives.
キャンプに折りたたみナイフを持っていく。
I take a folding knife when I go camping.
彼はポケットから折りたたみナイフを取り出した。
He took a folding knife out of his pocket.
Standard spelling using 折りたたみ (folding) and ナイフ (knife).
Alternate spelling with the kanji 畳 for たたみ; less common but still seen.
ポケットナイフ is a more general term for any small knife carried in a pocket, while 折りたたみナイフ specifically emphasizes the folding mechanism.
肥後守 is a traditional Japanese folding knife without a locking mechanism, often associated with schoolchildren in the past. 折りたたみナイフ is a broader, modern term.
Compound of 折りたたみ (folding) + ナイフ (knife). The word is a straightforward modern formation.