noun
fine line; thin line
Refers to a very thin line, often drawn or engraved. Also used figuratively for a delicate boundary.
職人が糸目のような細い線を彫った。
The craftsman carved a line as fine as a thread.
この布にはもう少し糸目の太い糸を使ったほうがいい。
For this fabric, it's better to use a slightly thicker thread.
noun
slit-eyed; narrow-eyed
Colloquial and often vulgar term for eyes that are very narrow, like slits. Can be derogatory.
あの男は糸目で、いつも何を考えているかわからない。
That guy has slit eyes, and you never know what he's thinking.