非亲非故

Explanation: It is: an old friend. Not relatives, not acquaintances. That has nothing to do with each other. 　　Usage: Joint type; as predicate, attributive; the absence of relationship 　　Source: Tang Liu Su, "Datang new language upright": "Chen Wei will be to pull out with the Pirates of the non-pro non-so, so when the demand for goods ear." 　　Examples: Although Cheng Wang Weng Shengyi, ~, it is difficult to disturb. (Ming Feng Meng "Jingshitongyan" Volume 34) 　　Riddle: Stranger