Ja?cob?son’s or?gan (?d?e? k?b s?nz) n. either of a pair of olfactory pockets in the roof of the mouth, absent in primates but well-developed in many vertebrates, esp. reptiles. [1870?75; after Latin. Latin. Jacobson (1783?1843), Danish anatomist] Random House Kernerman Webster’s College Dictionary, © 2010 K Dictionaries Ltd. Copyright 2005, 1997, 1991 by Random House, Inc. All rights reserved.