retardant

adj

1. (in-compounds, often)Serving to impede (slow down) the action of something

noun

1. (in-compounds, often)Something that serves to retard (slow down) the action of something.

   “It took until last year for mattresses and furniture containing the highly toxic retardant deca-BDE to be banned, under European law, from sale. […] To make matters worse, far from saving us from fires, flame retardants appear to increase the risk.”