Isoceth-10 is a substance used in cosmetic formulations. Isoceth-10 acts as emulsifier (changes the interfacial tension of liquids like water and oil so that they can be mixed together) and surfactant.
Isoceteth(s) are the polyoxyethylene ethers of isocetyl alcohol (for comparison see: laurethe as polyoxyethylene ether of lauryl alcohol; steareth as polyoxyethylene ether of stearyl alcohol and others).