Spike heels are the common term used for formal high-heeled shoes with slim heels. Synonyms for spike heels include stilettos, pencil heels, needle heels, slim heels, and high heels. Stilettos are known for their thin and high heel, while pencil heels are similar but tend to be slightly wider. Needle heels are also a synonym for spike heels, known for their pointed edge. Slim heels are the most general term for any type of thin heel, and high heels generally refer to any shoe with a heel of over three inches. Regardless of the name, all of these shoes are designed to elongate and accentuate the legs of the wearer.