How is 들어가다 used as a farewell greeting?

Question

From what I understand 들어가다 means "to go inside" (with 들어오다 meaning come inside)

But I have seen conversations like this is basic Korean books:

가: 먼저 들어가겠습니다. 안녕히 계세요.

나: 안녕히 가세요. 조심히 들어가세요. 내일 봅시다.

How is 들어가다 a farewell greeting? When I look up 들어가다 in English to Korean dictionary, non of the meanings seem to be a farewell.

What exactly does it mean as a farewell? What is the word root?

Answer 1

들어가다 in a farewell greeting is very common. As you said, it literally means "to go inside," and its usage in this situation typically implies going into one's home (to sleep at the end of the day, for example) (or into whatever place would appropriately end the contact)

• If you're eating dinner with colleagues and you leave first:

먼저 들어가겠습니다 = "I'll be going (home) first."

• If you're taking a smoke break at the office, and you're about to go back inside (back to work).

들어가겠습니다 = "I'm going (back inside the office)."

However, in practice it is often used as sort of an idiom; one can use it for a goodbye even if it's clear he doesn't intend to go directly into somewhere. In this respect, it's just a saying more than an exact, literal statement.

Answer 2

It implies that the person is returning home (literally go into their house).

Etymology is vague but I've heard of two origins:

One from people meeting outside, in a coffee shop for example, and then when they part, they say they're returning home.

Another is from the old days when there were no home phones. You had to use public payphone to make a call and at the end of conversation, you'd say you will return home.

Answer 3

One of typical farewell is 안녕히 가세요.

But if his home is near, we can use

안녕히 들어가세요./살펴 들어가세요./조심히 들어가세요./올라가세요 (at elevator)

The origin of 들어가세요 is not clear : Note that there was one or two phones in a village so that we must go to a fixed place.

Hence after quitting a phone, he must returned to home so that at ending, they say 들어가세요.

Until recent, I found that old someone say 들어가 and quit the phone. And when old people go apart in cold place or bus station, they use 어여(quickly) 들어가.

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