this is specifically "four-way intersection", right?

Yes, and other ones are numbered too. I live near to an 오거리

trivia: word '네거리' is used in North Korea, which is exactly the same thing as 사거리 but written with a native Korean numeral (since 네 and 사 is a number four in both cases)

similarly, they use 세거리 for three-way intersection rather than 삼거리