Gk Marana tha, meaning "Our Lord, come!"
These Aramaic words can also be read Maran atha, meaning "Our Lord has come"
BibleWorks 8, 1 Cor. 16:22
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In scripture as well as in the Didache, the only form it is found is in the Greek μαραναθά; the Aramaic form is believed to either be maran atha 'Our Lord has come' or marana 'tha 'O our Lord, come thou'.
So while I'm no expert in Aramaic, it would seem from what I read in the OED that assuming the form you suggested maran would translate as 'Our Lord' and atha would translate the English Perfect 'has come'.
http://www.orthodoxchristianity.net/forum/
index.php?topic=13854.0
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"Maranatha" is the prayer word recommended by the World Community for Christian Meditation, the community of followers of the teaching of John Main OSB's teachings on the practice of Christian meditation. The prayer is one where one places everything aside: instead of talking to God, one is just being with God, allowing God’s presence to fill one's heart, thus transforming one's inner being. [1]
http://en.wikipedia.org/wiki/Maranatha
[1] "Heavenly Father, open our hearts to the silent presence of the spirit of your Son. Lead us into that mysterious silence where your love is revealed to all who call, 'Maranantha…Come, Lord Jesus'."
In 1976, shortly after he had begun his public teaching on meditation, John Main composed this prayer for his first set of tapes. Later it was published in his first book “Word into Silence”. In few words it expresses both the essence of the Christian understanding of prayer and the sense that we do not pray in isolation but also as members of the community of the Body of Christ.
Having at first been introduced to meditation through its universal tradition in the East many years before he had become a monk, he was experientially prepared to recognize the essential Christian expression of the teaching when he encountered it in the Conferences of John Cassian and the Christian medieval tradition in the late sixties. It was not, however until a few years later that he realized how deeply enriching and universal this approach to contemplation could be in the church at large.
At first he had seen it as a way of monastic renewal. But through his experience of teaching lay people of all ages and walks of life at his monastery in London he understood that here was a simple yet transforming practice of the prayer of the heart that could be followed as a gentle and daily discipline by all disciples of Jesus.
John Main’s theology of meditation is both Christocentric and profoundly Trinitarian as this prayer shows. He has been well called a ‘Trinitarian mystic’. Many individual meditators and meditation groups around the world today begin their silent meditation that takes them beyond all words with this short prayer which comprehends the mystery of silence in the experience of the God who is communion in love.
The mantra ‘maranatha’ that was John Main’s preferred recommendation to people beginning meditation is the oldest Christian prayer (it means ‘come, Lord’), in Aramaic, the language of Jesus, used by St Paul at the end of the First Letter to the Corinthians (16:22) and found in the earliest Christian liturgies.
http://www.wccm.org/item.asp?recordid=
openingprayer&pagestyle=default
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"maranatha" (a word from the ancient Aramaic language meaning "Lord of the heart"
http://www.oprah.com/article/spirit/
emotionalhealth/spirit_meditation_mantra_b1
