知音

zhīyīn
  1. intimate friend
  2. soul mate

CEDICT

  1. (literary, literal) to have a thorough understanding of music; to be proficient in music
  2. friend keenly appreciative of one's talents; bosom friend; intimate friend; soul mate
  3. to have a thorough understanding of music; to be proficient in music

Wiktionary

春秋时，俞伯牙善鼓琴，锺子期善听琴。当伯牙弹琴志在高山时，子期便从琴音感到峨峨若泰山；当伯牙志在流水时，子期又感到洋洋若江河。子期死后，伯牙便绝弦不弹，因为再也没有人能像子期那样懂得他的音乐了。见《列子．汤问》。后比喻了解自己的知心朋友。

重編國語辭典

Entry Composition

1 知 zhī
  1. to know
  2. to be aware
2 音 yīn
  1. sound
  2. noise
  3. note (of musical scale)
  4. tone
  5. news
  6. syllable
  7. reading (phonetic value of a character)

Related entries

挚友 zhìyǒu
  1. intimate friend
  2. close friend
知交 zhījiāo intimate friend
腻友 nìyǒu intimate friend
知己 zhījǐ
  1. to know oneself
  2. to be intimate or close
  3. intimate friend
知己难求。

A real friend is like a rare bird.

Source: Tatoeba

同袍 tóngpáo
  1. fellow soldier
  2. comrade
  3. companion
  4. intimate friend