Lexicalization of "Xiong Di" for Brotherhood

In modern Chinese,"Xiong Di(兄弟)"is mostly used on the partial meaning of compound words,semantic bias toward "brother".In pragmatics it has the meaning of modest.In ancient Chinese,"Xiong"(兄) and "Di"(弟) can be used alone and express the different things.With the development of the language and effects of internal factors of language,they have appeared to be united phrases.The phrase "Xiong Di"(兄弟) has transformed to the disyllabic phrase and finally completed the lexicalization.