Definition of "thimerosal" [thimerosal]

• A cream-colored crystalline powder, C9H9HgNaO2S, used as a local antiseptic for abrasions and minor cuts. (noun)

American Heritage(R) Dictionary of the English Language, Fifth Edition. Copyright (c) 2011 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.

• "However, injected flu vaccines may contain thimerosal, a mercury-containing preservative, which many doctors believe is safe but others believe may be responsible for effects on the brain and nervous system."
• "Will the single-dose injectable units of H1N1 2009 vaccine that do NOT contain thimerosal (mercury) be available at the same time as the multi-dose vials that do contain it?"
• "For the record, thimerosal is not the only ingredient that worries those of us with autistic children."