n.
Pronunciation: - ˌ bi-ch ə - ' w ā -sh ə n, -chü- ' ā -
Function: noun
Date: 15th century
1 : the process of habituating : the state of being habituated
2 a : tolerance to the effects of a drug acquired through continued use b : psychological dependence on a drug after a period of use ― compare ADDICTION
3 : decrease in responsiveness upon repeated exposure to a stimulus