//===
region:
legion: large number of people, large military force, ...
religion:
pigeon: dove
//===
pigeon pair : 龍鳳胎
pigeon hole:
pigeon hole principle: 一山得容二虎 如果全世界只有一山的話
--> drawer principle/shelf principle
[ref]
http://www.nciku.com/search/all/pigeon
http://en.wikipedia.org/wiki/Pigeonhole_principle