Combine two antonyms like 来 come, 往 go; 买 buy, 卖 sell; 东 east, 西 west; 安 safety, 危 danger; etc. can form a new word, but the meaning of the compound is not always the literal combination of the two antonyms. There are several cases as to the relation between the meaning of the compound and the two antonyms.
1. The compound formed by two antonyms has figurative meanings
旦 morning and夕 evening combine to form 旦夕 in a short time, overnight. 手 hands and 足 feet combine to form 手足 brother, e.g. 他们亲如手足 they are as close as brothers.
2. The compound formed by two antonyms has the same meaning as one of the antonyms
3. The meaning of the compound is extended, generalized and abstracted on the basis of the meaning of the antonyms
4. The meaning of the compound is a combination of the meanings of the two antonyms
父 (father) and 子 (son) combine to form 父子 (father and son). 夫 (husband) and 妻 (wife) combine to form 夫妻 (husband and wife).
The characteristics of the compounds formed by two antonyms make them very unique in Chinese words. Compounds formed by two antonyms don’t have antonyms. Unlike others types of compounds, they have few synonyms.
Sometimes the pronunciation of one of the two antonyms will change to the neutral tone, e.g. 买卖 (business) should be read mǎi mai but not mǎi mài; 多少 (how many) should be read duō shao; 东西 (thing) should be read dōng xi. It can be the first word or the second that changes the tone.