- insufficiently active: an underactive thyroid gland.
Origin of underactive
Dictionary.com Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2018
Examples from the Web for underactive
An underactive thyroid, known as hypothyroidism, is caused by an inadequate production of thyroid hormone.When You Don't Know Where to Turn
Steven J. Bartlett
- (of the thyroid or adrenal glands) not functioning at full capacity
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