What does 一筋 mean in Japanese?

一筋 (ひとすじ) means a strand, a line, earnestly, single-mindedly.

What JLPT level is 一筋?

一筋 is a JLPT N1 vocabulary word.

a strand, a line, earnestly, single-mindedly

一筋 (ひとすじ, hitosuji) is a JLPT N1 vocabulary word meaning “a strand, a line, earnestly, single-mindedly”.

私わたしは妻つま一筋ひとすじです。

I'm faithful to my wife.

涙なみだが一筋ひとすじ頬ほおを流ながれた。

A tear ran down her cheek.

一筋ひとすじの光ひかりが窓まどから差さし込こんだの。

A beam of light shone through the window.

京都の西北に連なる鷹ケ峰、鷲ケ峰、釈迦谷山などの山稜から一筋の川が流れている。

There is a river running from mountain ridges, for example; Mt. Takagamine, Mt. Washigamine and Mt. Shakadani northwest of Kyoto.