chromosomal mosaicism: a chromosomal pattern in which some cells of the body have the standard number of chromosomes (46,XX or 46,XY), and others have more or less, as in 45,X/46,XY (a mosaic variety of Turner's syndrome); or 46,XY/47,XXY (a mosaic variety of Klinefelter's syndrome), and many others.
Dictionary of Sexology Project: Main Index