Abarim Publications' online Biblical Greek Dictionary
The preposition ανα (ana) means on or upon or in addition to. It occurs 15 times in the New Testament, see full concordance, and may be translated as "among" (tares among the wheat — Matthew 13:25) or "within" (a certain region — Mark 7:31). It may mean "each" (each a denarius — Matthew 20:9; each of the gates — Revelation 21:21). In Luke 10:1 occurs the term ανα δυο (ana duo), meaning "on two", or "each two", or as we say it in English: "two by two" or "in pairs".
The difference between ανα (ana) and the similar επι (epi), is that the latter emphasizes arrival at a boundary, whereas the former implies absorption.
In composite words our preposition commonly describes an up or upward, or repetitive motion (time upon time) and may as such be employed as a particle of emphasis — hence the Anabaptists (or "re-baptizers"), but also the words analogy and analogue (or "thing-to-thing correspondence") and analysis (or "loosen up/ wholly unfasten").