The term "acrylic" refers to any polymer made from derivatives of acrylic acid: CH2=CH-COOH. The C=C double bond here signifies that it can form polymers, when initiated by a suitable free radical initiator (or even UV light). The polymers are characterised by being hard and tough.

The term also includes compounds where there are substituents on the alpha-carbon atom, such as methacrylic acid, (CH2=C(CH3)-COOH), its ester, methyl methacrylate (PMMA is a hard transparent plastic - "lucite" & "perspex") and others such as 2-ethyl hexyl acrylate, which is copolymerised with vinyl acetate to make latex (or emulsion) paints. The purpose of the 2-ethyl hexyl acrylate is to lower the film forming temperature so that the paint still forms films on a cold day. Other derivatives of acrylic acid include acrylamide that forms strong fibers when polymerized (and is also implicated as a carcinogen in barbecued food and other high-baked goods!). When acrylamide is "pyrolized" in the absense of oxygen, we are left with a chain of carbon atoms and we get "carbon fibers."