deponent

Having an active meaning, but conjugating as though it were being used with a different voice (such as the passive).

A witness; especially one who gives information under oath, in a deposition concerning facts known to him or her.

The said William Aitken, being of new solemnly sworn, &c., depones he is a Burgess of Hawick, and had the property of a house which he now liferents, the fee being disponed to his son-in-law, Bailie Robert Scot, for the use of his son William, his daughter, Bailie Scot's wife, having paid the price of the house; depones sixty years ago Gilbert Elliot was tenant in Nether Southfield, who broke Hawick Common by plowing a part of it, which the Deponent saw at the Common-Riding when the Magistrates and other persons at the Common-Riding potched the ground he had plowed, and was then sown that he might not reap the crop of this.

A deponent verb.