1.
line, stripe, streak
A thin line or mark on a surface.
白い筋が入った石を拾った。
I picked up a stone with white streaks in it.
空に飛行機雲の筋が見える。
You can see a contrail streak in the sky.
涙の筋が頬に残っていた。
Tear streaks were left on her cheeks.
2.
muscle, tendon, sinew
Muscle fibers or tendons in the body.
筋肉の筋を痛めた。
I strained a muscle.
足の筋を伸ばしてから走ろう。
Let's stretch our leg muscles before running.
首の筋を違えてしまった。
I pulled a muscle in my neck.
3.
plot, storyline
The main story or sequence of events.
この映画の筋を教えて。
Tell me the plot of this movie.
話の筋が分からなくなった。
I lost track of the storyline.
あらすじだけでは筋の面白さは伝わらない。
The charm of the plot can't be conveyed through a summary alone.
4.
logic, reason, principle
A coherent line of reasoning or proper procedure.
それは筋が通らない。
That doesn't make sense. / That's illogical.
筋を通して話さないと、相手に失礼だ。
It's rude if you don't follow proper procedure when speaking to the other party.
あの人の言うことはいつも筋が通っている。
What that person says always makes logical sense.
筋 has multiple related meanings centering on the concept of a "line" or "thread."
COMMON EXPRESSIONS:
- 筋が通る (to make sense, to be logical)
- 筋を通す (to follow proper procedure)
- 筋違い (irrelevant, off-topic; also: muscle strain)
COMMON COLLOCATIONS:
- 血筋 (bloodline, lineage)
- 道筋 (route, path)
- 話の筋 (storyline)
- 筋肉 (muscle)
SENSE CONNECTIONS:
The meanings are connected through the idea of a continuous line: physical lines → muscle fibers → storyline → logical thread.