the GNU version of the Collaborative International Dictionary of English
ad. On that or this.
The Century Dictionary and Cyclopedia
On that.
WordNet 3.0 Copyright 2006 by Princeton University. All rights reserved.
ad. on that
Word Usage
"Then he gave orders to sweep a bench behind the door and, spreading on it a sitting-rug and a leather-cloth, seated Nur al-Din thereon and loosed his shackles and entreated him kindly."