lǎopo (老婆); he disapproved of that one, too common!
fūrén (夫人), too formal for everyday use.
taitai (太太), polite and rather formal, also means "Mrs."
qīzǐ (妻子); he uses that one for his wife, when talking to friends
xǐfu (媳妇), ... or this one
xǐfu r (媳妇儿), young wife
airén (爱人), lit. "love person"
An Emperor's wife (concubine) would have been his fēizi (妃子).
Then there are the words for people's unofficial wives or mistresses. Nǔpéngyǒu (女朋友) is "girlfriend," but if a man's already married to someone else, he might call the mistress his xiǎo sān r (小三儿) i.e. "little number three" (the phrase used to be used for the third child in a family, in the days when such a thing was allowed), or his èrnǎi (二奶) lit., "number two breast", as opposed to his dànǎi (大奶), lit. "big breast", i.e. the wife, again. The latter are not very polite words; my teacher was obviously embarrassed by them and apologised for his bad language!
Isn't that an extraordinary list, and interesting?
Thursday, January 17th
Interestingly, those ways of calling wife is happened in different time or different places (south, north, etc.) My dad calls my mum" ài rén" when he introduced my mum to new friends, but nowadays we normally call wife "lǎo po" in our generation. I guess your teacher is a funny man; he even taught you "xiǎo sān" and "èr nǎi." Those all the illegal lovers (not wife) exist in China, common and healthy family won't have those, those words just showed in society recently, say less than 20 years; they were new built words for that twist phenomenon. My grandpa's generation or even early called wife as" nèi rén" 内人 which means the person inside his house. Funny, isn't it? We won't use this anymore now though.