overleaven

From over- +‎ leaven.

overleaven (third-person singular simple present overleavens, present participle overleavening, simple past and past participle overleavened)

1. To leaven too much.
2. (obsolete, by extension) To change excessively; to spoil.

• “overleaven”, in Webster’s Revised Unabridged Dictionary, Springfield, Mass.: G. & C. Merriam, 1913, →OCLC.