The Character - 宅 (Zhái)

The word 宅 (Zhái) in Mandarin is referring to a residence, a house, or a mansion. 
Some of the commonly seen vocabulary or terms associated with this word include:

豪 宅 (Háo Zhái) =a luxurious mansion 

宅 院 (Zhái Yuàn) = a house with a courtyard 

宅 邸 (Zhái Dĭ) = a formal way of saying a residence

Nowadays, due to the influence of Japanese anime, manga, and computer games, the Chinese have extended the usage of this word to describe people who stay home most of the time with limited social interaction. 

Such usage is derived from the Japanese term, OTAKU, written as 御宅族 and pronounced as "Yǜ Zhái Zú" in Mandarin Chinese. It is referring to those who are fanatic about anime, manga, and gaming. This group of people are often young, and they usually stay in the house for most of the time, in front of a computer or a TV set.

Examples of modern Chinese usage:

他 很 宅 (Tā Hěn Zhái) = He is a person who stays home all the time 

宅 男 (Zhái Nán) = a boy / man who stays home most of the time 

宅 女 (Zhái Nǚ ) = a girl / woman who stays home most of the time