The status of the principal wife and concubine differed greatly.
Tips
history
In Chinese family law before 1950, a household had one 正室 (principal wife) but could have multiple 妾室. Wives entered through formal marriage; concubines through 纳 - a transactional 'taking in.' The 1950 Marriage Law abolished concubinage.
register
Historical / literary. Common in costume dramas (古装剧) and Qing-dynasty novels. Modern Chinese has no living equivalent - illicit relationships use 二奶 (mistress) or 小三 (the third party).
