μεσοβασιλεύς
μεσοβασιλεύς, interrex, one who holds kingly power between death of one and accession of another
Alas! Could not find the search term μεσοβασιλεύς.
Found the closest form μεσοίη. Other nearby forms can be found in the wordwheel, or perhaps try searching again without accents.
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Parsed as:
✓ present active optative 3rd singular of μεσόω
No checked forms of μεσοβασιλεύς in the morphology database.