General term for a knife, typically a Western-style table knife or pocket knife. For traditional Japanese knives, 包丁 (ほうちょう) is more common.
ステーキを食べるときはナイフとフォークを使います。
I use a knife and fork when eating steak.
He took a small knife out of his pocket.
He cut the apple with a knife.
I sharpened the knife before cooking.
The man stabbed a passerby with a knife.
bread knife