subthreshold

[ suhb-thresh-ohld, -thresh-hohld ]
/ sʌbˈθrɛʃ oʊld, -ˈθrɛʃ hoʊld /

adjective Psychology, Physiology.

(of a stimulus) too weak to produce a response.

Origin of subthreshold

First recorded in 1940–45; sub- + threshold
Dictionary.com Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2019