[ dahy-uh-ster-ee-uh-mer, -steer- ]
/ ˌdaɪ əˈstɛr i ə mər, -ˈstɪər- /

noun Chemistry.

either of a pair of stereoisomers that are not mirror images of each other.
Compare enantiomer.

Origin of diastereomer

First recorded in 1935–40; dia- + stereo(iso)mer
Also called di·a·ster·e·o·i·so·mer [dahy-uh-ster-ee-oh-ahy-suh-mer, -steer-] /ˌdaɪ əˌstɛr i oʊˈaɪ sə mər, -ˌstɪər-/.
Dictionary.com Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2019

British Dictionary definitions for diastereoisomer

/ (ˌdaɪəˌstɛrɪəʊˈaɪsəmə) /


chem a type of isomer that differs in the spatial arrangement of atoms in the molecule, but is not a mirror image; a stereoisomer that is not an enantiomer
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