太太 (tài tài) means wife or Mrs and is a polite or slightly formal term. It is used both as a kinship term (我太太, my wife) and as an honorific address (王太太, Mrs Wang). It is more formal than 老婆 (lǎo pó), which is informal and intimate, and less clinical than 妻子 (qī zi), which is the standard written term for wife. 太太 is especially common in Taiwan and Singapore.