Aliya

These days this expression means the process of immigrating to Israel. Historically it meant Jews coming to live in the Holy Land and thus ascending spiritually.

A modern opposite, yeridah, lit. descent, has sprung up since about the 70's, and accurately denotes the surruptitiously (and sometimes not so...) antagonistic attitude Israelis are prone to have towards those of their numbers who choose to leave and seek their fortunes abroad.

Also, a term coined among jews for the immigrantion to The Land of Israel, which is considered a spiritual ascent (since Israel is the Holy Land). Similarily, Yeridah (descent) is a term for emigration from Israel, and thus spiritual descent.

It's source is in the Torah, from the verse telling how Abraham "went down (yarad) to Egypt".

Nowadays, it's used in modern colloquial Hebrew without any religious context. For example, the former-USSR emigrant looking for "shelter" in Israel would be called an Ole (ascender), while someone leaving Israel to seek fame and fortune in the US would be called a Yored (descender), and it wouldn't necessarily reflect the person's opinions of those countries.

Some politically correct anti-religious enforcement freaks would oppose those terms though and use the literal Hebrew word for "immigration" instead.