1. (Animals) any aquatic bird, such as Podiceps cristatus (great crested grebe), of the order Podicipediformes, similar to the divers but with lobate rather than webbed toes and a vestigial tail. [C18: from French grebe, grÃ¨be of unknown]. originrebe. n. Any of various swimming and diving birds of the family Podicipedidae, having a pointed bill and lobed, fleshy membranes along each toe. [French.
Popular Answers. 1  Productivity = Output / Input. Efficiency = Doing things right. 2  Productivity refers to the conversion level of inputs into outputs. A process that can produce more output using less inputs is more proactive. Efficiency in the economic sense mean that things should be done in an economic way considering that resources are scarce.
Productivity (ecology) In ecology, productivity or production refers to the rate of generation of biomass in an ecosystem. It is usually expressed in units of mass per unit surface (or volume) per unit time, for instance grams per square metre per day (g mâ2 dâ1). The mass unit may relate to dry matter or to the mass of carbon generated.