It's not a word, it's an abbreviation of the words מורנו הרב = מו"ה what you see on the tombstone is 'מוה
The abbreviation - in other contexts - indicates the person was an ordained rabbi. However, it sometimes appears on tombstones as a sign or respect or is even at times added because people saw it on other tombstones, and do not necessarily know what it means.
Don't treat it as proof of his rabbinical ordination, but as a trigger for further research into his status.
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Odeda Zlotnick
Jerusalem, Israel.