My concise Korean Language Dictionary by Geum-Seong [Planet Venus] Press defines it as:
1. 사람이 다른 사람이나 동물과 함께 오랫동안 지내 오면서 생기는 좋아하는 마음. 또는, 사람이 오래 살거나 생활해 온 곳에 대하여 가깝게 느끼는 마음.
[1. A fond feeling/mood that arises as one lives with another person or animal for a long time. Or, a feeling of closeness towards a place where one has been living or making a living for a long time.]
2. 특히, 남녀간의 애정.
[2. Tenderness, especially between men and women.]
3. 남을 도와주거나 배려하는 따뜻한 마음.
[3. A warm feeling/mood for helping or concerning oneself with others.]
4. '감정', '마음'을 가리키는 말.
[4. (A word signifying) 'feelings' or 'mood'.]
The first, and apparently most common, meaning could probably best be expressed in English along the lines of "we're very close", "we're old friends" or "we've known each other a long time", where other people are concerned. Referring to a thing, "(I've) had it for such a long time..." or "(I) feel like it's a part of (me)" expresses a similar sentiment.
한 (恨) han
Korean Language Dictionary definition:
억울하거나 원통하거나 원망스러워 쉽게 잊히지 않고 마음속에 단단히 응어리가 진 감정.
[A feeling not easily forgotton and firmly ingrained in one's heart from feeling unfairly treated or let down or bitter]
NB. Would you say this could be best said as "a grudge", "I feel bitter (about it)", "(it) leaves a bad taste in your mouth" or "hurt" (uncountable), or something else?
왕따 (王-) wang-tta
[Collectively harassing and excluding/ostracising a person, or the person who is ostracised.]
NB. This would seem to most closely fit the English words 'exclude', 'ostracise' or 'alienate' rather than, as most dictionaries would have it, 'bully' ('to hurt or frighten someone who is smaller or less powerful than you, often forcing them to do something they do not want to do' - Cambridge Advanced Learner's Dictionary).
1. 남의 마음이나 뜻을 그때그때의 상황으로 미루어 얼른 알아차리는 힘.
2. 미루어 짐작할 만하게 사람의 행동에 은근히 드러나는 어떤 태도나 뜻.
[2. An attitude or intention quietly revealed in a person's behaviour,
NB. 'Perceptiveness', 'intuition'; or simply 'alertness' 'being observant', 'being sensitive to someone's mood' or 'being on the ball'. (Therefore "눈치있네! --> You're very perceptive / observant!") What do folks out there reckon?