When the long-run average total cost curve is downward-sloping as output increases,the firm has diseconomies of scale.

Diseconomies of Scale

An economic concept referring to a situation where, as a firm expands, the costs per unit increase.

Long-Run Average Total Cost Curve

A graphical representation that shows the lowest average total cost at which a firm can produce any given level of output in the long run, where all inputs are variable.

Downward-Sloping

A term often used in economics to describe a curve or line that represents a decrease in one variable as another increases, typical in demand curves.