tempered glass
[¦tem·pərd ′glas] (materials)
Glass that has been prestressed by heating followed by sudden quenching to give it two to four times the strength of ordinary glass. Also known as toughened glass.
McGraw-Hill Dictionary of Scientific & Technical Terms, 6E, Copyright © 2003 by The McGraw-Hill Companies, Inc.
tempered glass
1. Annealed glass reheated to just below the softening point and then rapidly cooled with water. When fractured, it breaks into relatively harmless pieces. See also: Glass
2. 
Illustrated Dictionary of Architecture Copyright © 2012, 2002, 1998 by The McGraw-Hill Companies, Inc. All rights reserved
tempered glass
(US), toughened glass (Brit.) Glass having two to five times the strength of ordinary glass as a result of having been prestressed by heating and then suddenly quenched; the rapid cooling produces a compressively-stressed surface layer.
McGraw-Hill Dictionary of Architecture and Construction. Copyright © 2003 by McGraw-Hill Companies, Inc.