The English definition of a CC-CEDICT entry can contain references to other Chinese words.

1. If the traditional and simplified characters of the reference are the same, write it as 字[zi4].
2. If the traditional and simplified characters of the reference are different, write it as 漢字|汉字[han4zi4]

For example, here is an entry that contains multiple references:

六腑 六腑 [[liu4fu3]] /(TCM) the six hollow organs: gallbladder 膽|胆[dan3], stomach 胃[wei4], large intestine 大腸|大肠[da4chang2], small intestine 小腸|小肠[xiao3chang2], triple heater 三焦[san1jiao1], bladder 膀胱[pang2guang1]/

The referenced word does not necessarily need to be in CC-CEDICT.

These are special types of references that have their own syntax. If using this syntax, the referenced word does need to be in CC-CEDICT.

When the pinyin and at least one sense of two entries are the same, they are considered variants and we use the “variant of …” syntax.

鮮豔 鲜艳 [[xian1yan4]] /bright-colored; gaily-colored/
鮮艷 鲜艳 [[xian1yan4]] /variant of 鮮豔|鲜艳[xian1yan4]/

麒麟 麒麟 [[qi2lin2]] /(Chinese mythology) qilin/(old) giraffe/
騏驎 骐𬴊 [[qi2lin2]] /(literary) fine horse/variant of 麒麟[qi2lin2]/
騏麟 骐麟 [[qi2lin2]] /variant of 麒麟[qi2lin2]/

The “variant of …” syntax essentially means you can substitute the entire definition of the reference for the current sense. You could therefore write 麒麟 and its variants as

麒麟 麒麟 [[qi2lin2]] /(Chinese mythology) qilin/(old) giraffe/
騏驎 骐𬴊 [[qi2lin2]] /(literary) fine horse/(Chinese mythology) qilin/(old) giraffe/
騏麟 骐麟 [[qi2lin2]] /(Chinese mythology) qilin/(old) giraffe/

Generally, we try to put the definition on the more common word and the “variant of …” syntax on the less common ones.

When at least one sense of two entries are the same, they are considered synonyms and we use the “see …” syntax. If the pinyin is also the same, use the “variant of …” syntax.

麒麟 麒麟 [[qi2lin2]] /(Chinese mythology) qilin/(old) giraffe/
麟 麟 [[lin2]] /see 麒麟[qi2lin2]/

Just like with “variant of …”, the entire definition can be substituted for the sense.

It is not appropriate to use this syntax for all synonyms. For example, 高興|高兴[gao1xing4], 歡暢|欢畅[huan1chang4], 開心|开心[kai1xin1], and many other words are all synonymous for “happy”, but we would not have each entry simply say “see 高興|高兴[gao1xing4]” as each word has slightly different nuances or additional glosses that distinguish them. As a general rule, use the “see …” syntax when the definitions are exactly the same and when the Chinese characters making up the word are also very similar.

For example, we use this syntax when defining place names

青島市 青岛市 [[Qing1dao3 Shi4]] /Qingdao, sub-provincial city in Shandong Province 山東省|山东省[Shan1dong1 Sheng3]/
青島 青岛 [[Qing1dao3]] /see 青島市|青岛市[Qing1dao3 Shi4]/

or when the Chinese characters only differ slightly

天壤之別 天壤之别 [[tian1rang3 zhi1 bie2]] /lit. the difference between heaven and earth (idiom)/fig. night and day difference; a world of difference; a far cry (from)/
天淵之別 天渊之别 [[tian1yuan1 zhi1 bie2]] /see 天壤之別|天壤之别[tian1rang3 zhi1 bie2]/
霄壤之別 霄壤之别 [[xiao1rang3 zhi1 bie2]] /see 天壤之別|天壤之别[tian1rang3 zhi1 bie2]/

膻中穴 膻中穴 [[dan4zhong1xue2]] /(TCM) acupuncture point CV-17, located in the middle of the chest/
膻中 膻中 [[dan4zhong1]] /see 膻中穴[dan4zhong1xue2]/

甭 甭 [[beng2]] /need not; please don't (contracted form of 不用[bu4yong4])/
嘦 嘦 [[jiao4]] /(dialect) so long as; provided; if (contracted form of 只要[zhi3yao4])/
孬 孬 [[nao1]] /(dialect) no good (contracted form of 不好[bu4hao3])/