A cocktail dress is a knee- to midi-length dress worn for semi-formal occasions — think evening parties, weddings…
Cocktail = semi-formal, usually knee- to midi-length.
Evening/formal = longer, often floor-length, and more elaborate.
Fabric signals formality
satin and silk read dressier than cotton.
For cocktail attire, one refined dress plus heels and simple jewellery is enough.
See the pieces
Shop Cocktail Party Dresses from the boutique.