underactive

[uhn-der-ak-tiv]

Origin of underactive

First recorded in 1955–60; under- + active
Related formsun·der·ac·tiv·i·ty, un·der·ac·tive·ness, noun
Dictionary.com Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2018

British Dictionary definitions for under-activity

underactive

adjective
  1. (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