| 知己 | zhī jǐ | to know oneself; to be intimate or close; intimate friend |
海内存知己，
天涯若比邻 | hǎi nèi cún zhī jǐ ,
tiān yá ruò bǐ lín | close friend in a distant land, far-flung realms as next door (idiom); close in spirit although far away; absence makes the heart grow fonder |
| 知己知彼 | zhī jǐ zhī bǐ | Know yourself, know your enemy (idiom, from Sunzi's Art of War 孙子兵法) |
知己知彼，
百战不殆 | zhī jǐ zhī bǐ ,
bǎi zhàn bù dài | Know yourself and know your enemy, and you will never be defeated (idiom, from Sunzi's Art of War 孙子兵法). |
| 知彼知己 | zhī bǐ zhī jǐ | to know the enemy and know oneself (idiom, from Sunzi's Art of War) |
知彼知己，
百战不殆 | zhī bǐ zhī jǐ ,
bǎi zhàn bù dài | Knowing the enemy and yourself will get you unscathed through a hundred battles (idiom, from Sunzi's Art of War). |
| 红颜知己 | hóng yán zhī jǐ | close female friend; confidante |
| 蓝颜知己 | lán yán zhī jǐ | close male friend; confidant |
| 视为知己 | shì wéi zhī jǐ | to consider sb as close friend (idiom); to take into one's confidence |
