[Nyororin]

Today I encountered one of my personally most irritating synonyms, and it got me thinking... There must be a lot of others that are frustrating to learners of Japanese.
I invite everyone to toss out their most frustrating, and tell about why it is personally frustrating. It doesn't have to be a perfect synonym - words that are very close in sound or in writing are fine as well.

To start it off, I will list my own.

私立 vs. 市立
They are both read as しりつ... But they have nearly opposite meanings.
私立 is private... Like a private school, or a privately run/funded facility.
市立, on the other hand, is a public, city run facility.

Normally you don't encounter them in situations where they would be mistaken for each other that often. 国立 (nationally run) is a lot more common than 市立.
However, close to me there is a 市立図書館 and a 私立図書館. There is a 私立保育園 and a 市立保育園. A 私立幼稚園 and a 市立幼稚園. A 市立病院 and a 私立病院...

And people will say しりつの方 as if that helps. And it isn't just me who has trouble with this. I have watched other native speakers have a conversation like this:
今日病院行かないと
どこの？ 買い物行くから送っとくか？
しりつの方
どっちの？ 駅近くの？
いや、高速向こうのしりつ