Allahumma

' is an arabic term of address for Allah, in Islam. The word is not Arabic, but is one of the words that was Arabized from a foreign language. Ibn Ashur, in his explanation of Sūrat ʾĀl ʿImrān, suggests that the word Allāhumma is of Hebrew or of Qaḥṭāni derivation. It is possible, as Margoliouth notes that it is the Heb. word which had become known to the Arabs through their contacts with Jewish tribes.
Elohim' is a Hebrew word meaning "gods" or "godhood". Although the word is plural in form, in the Hebrew Bible it most often takes singular verbal or pronominal agreement and refers to a single deity, particularly but not always the God of Judaism. In other verses it takes plural agreement and refers to gods in the plural.
It is translated as "O Allāh" and is seen as the equivalent of "Yā Allāh". Some grammarians argue that it is an abbreviation of يا ألله أمّنا بخير ; others have argued without explanation that the suffix ـ مَّ takes the place of yā.

Christian usage

, a 9th-10th—century Christian Visigothic author in Al-Andalus, translated the Biblical Psalms into Arabic.
Rather than using the standard word for God, "Allah", he used or inspired by the Hebrew word.