Sleeves with no pleats or shirring at the base of the arms and a flare towards the hem. Typically the sleeves are shaped like a bell from the elbow to the wrist with long sleeves, and flare at the shoulder with short sleeves.
It should be noted that sleeves with puffy shoulders should not be tagged as bell sleeves. Juliet, Puff, or puff and slash sleeves sleeves should be used instead.