ETYMOLOGY
from past participial stem of Latin mussitare (to mutter),
from mussare (to mutter) + –itare (-itate)
EXAMPLE
“…those I meane which are not Neutralizers (if any such heare mee this day) Neutralizers, I say, or Interim-ists; such as dare secretly mutter and mussitate; Rome and the Reformed Churches agree in the substance of Religion, that there is no fundamentall difference betwixt them and vs; and againe that they teach no Heresies; …”
From: A Sermon Preached at Paules Crosse Laying open the Beast, and his Marks
By Richard Sheldon, 1625
Lexicophilia 