Cis may have the following meanings: "Cis" can be a noun or prefix, meaning "on the same side [as]" or "on this side [of]", with several derived usages In chemistry, cis refers to cis-trans isomerism In music, cis is another name for the note C♯ (C-sharp) In the mathematics of complex numbers, cis θ is an abbreviation for cos θ + i·sin θ Cis, Italy, a commune in the province of Trento, Italy Cis is an abbreviation for cisgender, a term used to describe gen… (More on Cis)