Medical Dictionary
Main Entry:
di·a·ste·reo·mer Pronunciation:
"dI-&-'ster-E-O-(")m&r, -'stir- Variant:
or di·a·ste·reo·iso·mer /-"ster-E-O-'I-s&-m&r, -"stir-/ Function:
noun : an isomer that is a stereoisomer of a compoundhaving two or more chiral centers and that is not a mirror image of another stereoisomer of the same compound —
di·a·ste·reo·mer·ic /-"ster-E-O-'mer-ik, -"stir-/ or di·a·ste·reo·iso·mer·ic /-"I-s&-'mer-ik/ adjective —
di·a·ste·reo·isom·er·ism /-I-'säm-&-"riz-&m/ noun
[dahy-uh-ster-ee-uh-mer, -steer-] 
əˈstɛr