1) Ester of a poison 2) Poisonous salt 3) Salt 4) Salt of a poison 
The arsenate ion is AsO43−. An arsenate (compound) is any compound that contains this ion. Arsenates are salts or esters of arsenic acid. The arsenic atom in arsenate has a valency of 5 and is also known as pentavalent arsenic or As[V]. Arsenate resembles phosphate in many respects, since arsenic and phosphorus occur in the same group (column) o...
• (n.) A salt of arsenic acid.
Ar'se·nate noun (Chemistry) A salt of arsenic acid. 
Arsenate refers to minerals in which a compound of arsenic and oxygen (AsO4) is an important part.
[n] - a salt or ester of arsenic acid
noun a salt or ester of arsenic acid
a salt or ester of arsenic acid.