From Computational Biology Group
A world clock is a power tool used to indicate , keep, and co-ordinate time. The http://worldclocksite.com is derived ultimately (via Dutch, Northern French, and Medieval Latin) from the Celtic words clagan and clocca meaning "bell". A silent instrument missing such a mechanism has traditionally been known as a timepiece. In general usage today a "clock" refers to any device for evaluating and displaying the time zones. Watches and other timepieces that can be carried on one's somebody are often distinguished from clocks.