1. The dry weight of living organic matter in a particular ecosystem: The units of biomass are grams of organic matter per square meter.

2. Plant-derived material usable as a renewable energy source: Biomasses can be produced from wood energy crops, such as hybrid poplars and willow trees. Biomasseses can also be obtained from agricultural crops like soybeans and corn, and animal and other wastes.

Biomass is one of the two most common energy sources in the U.S. today, along with hydropower. Forms of biomass, such as wood, can be burned to produce heat and generate electricity.

Agricultural crops can be chemically converted into fuels, such as ethanol and biodiesel. These are the only known renewable liquid energy sources, and may one day replace petroleum and fossil-fuel.

Organic substances from living organisms that were recently alive, particularly of vegetation, and used as a fuel: Biomass is also especially cultivated for the purpose of fuel or as a source of energy.

Biomass is can be used to produce biofuel that is made from this organic material.

A technology that extracts heat energy from biomass: By using the method of biomass combustion, a variety of power applications can be produced, like electricity!

Scientific research into future energy sources via biomass elements.

A general term for renewable energy produced from biomass: Biomass energy can be produced by using wood and wood wastes, agricultural crops and refuse, or municipal and industrial debris.

Any solid, gaseous, or liquid fuel obtained from biomass: Biomass fuel may be in its natural form (wood or peat) or from a commercially produced form (ethanol from sugarcane residue or diesel fuel from waste vegetable oils).

The total mass of living organisms present in a given area.

It may be specified for a particular species; such as, earthworm biomass or for a general category; such as, herbivore biomass.

Estimates also exist for the entire global plant biomass and measurements of biomass can be used to study interactions between organisms, the stability of those interactions, and variations in population numbers.

Whenever dry biomass is measured, the material is dried to remove all water before weighing.

A biomass energy feedstock in the form of lipids from animal fats, fish, and poultry oils, plant oils, or recycled cooking greases.

Any form of organic material that can be used as an energy source; such as, forest, mill, and agricultural residues, urban wood wastes, and dedicated energy crops.

An estimate of the quantities of such resources that are available by location and price levels: Biomass resource assessments must consider different factors, like practical obtainability and technical practicability, among others, to determine the usefulness of using biomass as an energy.

Organic non-fossil material of biological origin that is a byproduct or a discarded product: Biomass waste includes municipal solid waste from biogenic sources, landfill gas, sludge waste, agricultural crop byproducts, straw, and other biomass solids, liquids, and gases; but it excludes wood and wood-derived fuels (including black liquor), biofuels feedstock, biodiesel, and fuel ethanol.

It should be noted that some so-called biomass waste also includes energy crops grown specifically for energy production, which would not normally be considered waste.

Described as being a biomass between 10,000 and 100,000 times greater than the general abyssal environment.

Just like an oasis in the desert, these toxic sites attract an entire peripheral fauna constituted of sessile crustaceans; such as, the vent barnacles, which resemble a flower, or mobile crustaceans, like spider crabs.

The total quantity or mass of living material within a specified area of the ocean at a given time.

The concept of biomass allows people to express the idea of the abundance of animal presence in volume without having to use headcounts as is the case when speaking of density.

It is useful in that living organisms vary too broadly in size for density to be a meaningful measure.