Maran-atha - Vine's Expository Dictionary of New Testament Words
Maran-atha[ 1,,G3134, maran-atha ]
an expression used in 1 Corinthians 16:22, is the Greek spelling for two Aramaic words, formerly supposed by some to be an imprecatory utterance or a curse reinforced by a prayer," an idea contrary to the intimations coveyed by its use in early Christian documents, e.g., "The Teaching of the Apostles," a document of the beginning of the 2nd cent., and in the "Apostolic Constitutions" (vii. 26), where it is used as follows: "Gather us all together into Thy Kingdom which Thou hast prepared. Maranatha, Hosanna to the Son of David; blessed is He that cometh, etc."
The first part, ending in 'n,' signifies "Lord;" as to the second part, the Fathers regarded it as a past tense, "has come." Modern expositors take it as equivalent to a present, "cometh," or future, "will come." Certain Aramaic scholars regard the last part as consisting of 'tha,' and regard the phrase as an ejaculation, "Our Lord, come," or "O Lord, come." The character of the context, however, indicates that the Apostle is making a statement rather than expressing a desire or uttering a prayer.
As to the reason why it was used, most probably it was a current ejaculation among early Christians, as embodying the consummation of their desires.
"At first the title Marana or Maran, used in speaking to and of Christ was no more than the respectful designation of the Teacher on the part of the disciples." After His resurrection they used the title of or to Him as applied to God, "but it must here be remembered that the Aramaic-speaking Jews did not, save exceptionally, designate God as 'Lord'; so that in the 'Hebraist' section of the Jewish Christians the expression 'our Lord' (Marana) was used in reference to Christ only" (Dalman, The Words of Jesus).