1) Controller 2) Restrainer 3) Someone who suppresses 4) Suppresser 1) Retardant 2) Suppresser 
A suppressor, sound suppressor or silencer is a device attached to or part of the barrel of a firearm or air gun which reduces the amount of noise and visible muzzle flash generated by firing. Suppressors are typically constructed of a metal cylinder with internal mechanisms to reduce the sound of firing by slowing the escaping propellant gas and ...
• (n.) One who suppresses.
a component specially designed for disturbance suppressionelectronic component especially designed for disturbance suppression
A compound that suppresses the effects of mutation or suppresses what would be a normal course of events. ... (05 Mar 2000) ... 
A mutation that restores wild-type phenotype without affecting the mutant gene, usually arising by mutation in another gene.
Sup·press'or noun [ Latin , hider.] One who suppresses. 
Aircraft designated to employ ordnance against defenses.
Type: Term Pronunciation: sū-pres′ŏr Definitions: 1. A compound that suppresses the effects of mutation or suppresses what would be a normal course of events.
[n] - someone who suppresses 2. [n] - a gene that suppresses the phenotypic expression of another gene (especially of a mutant gene) 3. [n] - an electrical device for suppressing unwanted currents
suppresser noun an electrical device for suppressing unwanted currents