Noah Webster's Dictionary (a.) Being in the middle, or nearest the middle; midmost.

Multi-Version Concordance Middlemost (2 Occurrences) Ezekiel 42:5 Now the upper chambers were shorter: for the galleries were higher than these, than the lower, and than the middlemost of the building. (KJV JPS ASV WBS) Ezekiel 42:6 For they were in three stories, but had not pillars as the pillars of the courts: therefore the building was straitened more than the lowest and the middlemost from the ground. (KJV JPS ASV WBS)