Elohim is the commonest word for God in the Hebrew Bible, and it is grammatically plural. Used of the God of Israel it takes singular verbs, and the plural form is generally read as one of magnitude rather than of number. Used of other beings it takes plural verbs and means gods, or divine beings, or in a few passages something closer to powers: the assembly of Psalm 82 has God standing in the congregation of El and judging in the midst of elohim, and whatever those elohim are, they are not the speaker.
Taking that word as the name of one angelic rank among ten is a strong move. It applies to a class of subordinate beings a term that elsewhere names the God they serve, and it does so without any of the qualification a later theology would want. The ranked lists do not explain the choice, and the older material they draw on does not explain it either.
The ambiguity was already ancient when the ranking was made, and the ranking does not resolve it. That is the useful thing to know about this order: what the elohim of Psalm 82 and of the divine council passages actually are is a live question in biblical scholarship, with readings that run from gods of the nations to human judges to members of a heavenly court, and none of that argument is settled by the word being given a fixed place in a medieval hierarchy. The rank inherits the position without inheriting an answer.