A get-together is a small, friendly meeting where people come to see each other — not a big official event and not always a loud party. It can be at someone’s home, in a café, or in a park. There may be food, but there does not have to be music or dancing; classmates catching up after a long time is already a get-together. The word is informal and warm. A meeting has an agenda; a get-together has people. The noun comes from the phrasal verb get together (“Let’s get together next week”). You would not use it for a wedding, a conference, or anything stiff.