Cepheid variable (?si?f??d) n (Astronomy) astronomy any of a class of variable stars with regular cycles of variations in luminosity (most ranging from three to fifty days). There is a relationship between the periods of variation and the absolute magnitudes, which is used for measuring the distance of such starsCollins English Dictionary ? Complete and Unabridged, 12th Edition 2014 © HarperCollins Publishers 1991, 1994, 1998, 2000, 2003, 2006, 2007, 2009, 2011, 2014Ce?pheid var`iable n. a variable star with a short period of 1 to 50 days in which changes in brightness are due to alternations in volume. [1900?05; Cephe (us) + -id1] Random House Kernerman Webster’s College Dictionary, © 2010 K Dictionaries Ltd. Copyright 2005, 1997, 1991 by Random House, Inc. All rights reserved.