1) Chlorpyrifos 
An organophosphate (sometimes abbreviated OP) or phosphate ester is the general name for esters of phosphoric acid. Many of the most important biochemicals are organophosphates, including DNA and RNA as well as many cofactors that are essential for life. Organophosphates are the basis of many insecticides, herbicides, and nerve agents. The United ...
(or″gә-no-fos´fāt) an organic ester of a phosphate such as phosphoric acid with an organic compound such as glucose or sorbitol; see also organophosphorus. adj., organophos´phorous., adj.
Class of insecticides derived from phosphoric acid esters that act as inhibitors of the enzyme cholinesterase.
[n] - an insecticide that interferes with an insect`s nervous system
noun an insecticide that interferes with an insect`s nervous system
any of a variety of organic compounds that contain phosphorus and often have intense neurotoxic activity: originally developed as nerve gases, now widely used as insecticides and fire retardants. Also called