Thayer's Greek Lexicon

 1. up, upwards, above, on high
2. of the quarters of the heaven, northward
3. of countries, inland, up from the coast
4. of time, formerly

++++
In Gal. 4:26 the word could refer to either place or time,
i.e. place - the Jerusalem which is above - in the heavens
time - the eternal Jerusalem which preceded the earthly one