The word tabernacle means "dwelling place." Any place someone dwells is a tabernacle. The term is also sometimes used for a temporary dwelling place. Thus the tent-like sanctuary that the Jews used before the Temple was built was called the Tabernacle, because God dwelt there. Similarly, for the feast of Sukkot the Hebrews erected temporary shelters to live in for the festival, which is often called "the feast of tabernacles" or "the feast of booths" as a result.

The tabernacle in Church is so named because it is a place where Christ dwells in the Eucharist.

Source:http://www.catholic.com/quickquestions/what-is-a-tabernacle