Definition of "thiouracil" [thiouracil]

• A white crystalline compound, C4H4N2OS, that interferes with the synthesis of thyroxine, used to reduce the action of the thyroid gland, especially in the treatment of hyperthyroidism. (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.

• "By altering the nucleotide analog 4-thiouracil, the UPRT enzyme caused RNA to become tagged with thiouracil (TU), allowing the "TU-tagged" RNA to be purified from untagged RNA."