a hand, usually a second hand, centrally mounted with the minute and hour hands of a timepiece and reaching to the edge of the dial.
Origin of sweep hand
First recorded in 1940–45
Dictionary.com Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2019
horology a long hand that registers seconds or fractions of seconds on the perimeter of the dial
Collins English Dictionary - Complete & Unabridged 2012 Digital Edition © William Collins Sons & Co. Ltd. 1979, 1986 © HarperCollins Publishers 1998, 2000, 2003, 2005, 2006, 2007, 2009, 2012