定 vs. 订 both mean "sign", so, what's the difference?
what is the difference?

if i sign a contract etc., how do i say?

which of them is used in the situation when i need to sign a document?

Question

定 vs. 订  both mean "sign", so, what's the difference?
what is the difference?

if i sign a contract etc., how do i say?

which of them is used in the situation when i need to sign a document?

Answer

Both of them are verbs. 定 has the meaning of "decide". 订 has the meaning of "book" .
normally, they can be exchanged with each other, but in the situation get relation with law,  they have a big difference.

定， means the conditions are confirmed already, they can not be revised any more. It emphasize result. For example, 定金，定购。
订， means the conditions are  just a agreement, they may be revised. It emphasize the PROCESS. For example. 订婚，订货。

定价，can not be 订价。

Answer

sign a contract or document：签订合约/文件

Answer

● 定 

dìng 

◎ 不动的，不变的：～额。～价。～律。～论。～期。～型。～义。～都（dū）。～稿。～数（shù）（ａ．规定数额；ｂ．指天命；ｃ．规定的数额）。断～。规～。鉴～。 

◎ 使不变动：～案。～罪。决～。确～。 

◎ 平安，平靖（多指局势）：大局已～。 

◎ 镇静，安稳（多指情绪）：心神不～。 

◎ 确凿，必然的：必～。镇～。 

◎ 预先约妥：～计。～情。～货。～做。 

◎ 姓。 


订 

（訂） 

dìng 

◎ 改正，修改：～正。考～。校（jiào ）～。修～。 

◎ 约定，立（契约）：～立。～购。～约。 

◎ 用线、铁丝、书钉把书页、纸张连在一起：装～。 

◎ 制定：～计划。 


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Answer

to sign with your name = 签名

I've never seen 定 or 订 used for "sign".