knock-out

in biology
https://doi.org/10.1351/goldbook.15846
Technique used to inactivate a particular gene in a living organism in order to define its function.
Note: In mammalian toxicology, this technique is most readily applied to the mouse.
Source:
PAC, 2007, 79, 1153. (Glossary of terms used in toxicology, 2nd edition (IUPAC Recommendations 2007)) on page 1249 [Terms] [Paper]