[ bahy-oh-mas ]

  1. Ecology. the amount of living matter in a given habitat, expressed either as the weight of organisms per unit area or as the volume of organisms per unit volume of habitat.

  2. Energy. organic matter, especially plant matter, that can be converted to fuel and is therefore regarded as a potential energy source.

Origin of biomass

First recorded in 1930–35; bio- + mass

Words Nearby biomass Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2024

How to use biomass in a sentence

British Dictionary definitions for biomass


/ (ˈbaɪəʊˌmæs) /

  1. the total number of living organisms in a given area, expressed in terms of living or dry weight per unit area

  2. vegetable matter used as a source of energy

Collins English Dictionary - Complete & Unabridged 2012 Digital Edition © William Collins Sons & Co. Ltd. 1979, 1986 © HarperCollins Publishers 1998, 2000, 2003, 2005, 2006, 2007, 2009, 2012

Scientific definitions for biomass


[ ō-măs′ ]

  1. The total amount of living material in a given habitat, population, or sample. Specific measures of biomass are generally expressed in dry weight (after removal of all water from the sample) per unit area of land or unit volume of water.

  2. Renewable organic materials, such as wood, agricultural crops or wastes, and municipal wastes, especially when used as a source of fuel or energy. Biomass can be burned directly or processed into biofuels such as ethanol and methane. See more at biofuel.

a closer look

When biologist J.B.S. Haldane was once asked if the study of life on Earth gave him any insights into God, he replied jokingly that his research revealed that God must have “an inordinate fondness for beetles.” Haldane's comment is based on the fact that there are more beetle species-almost 400,000 now known-than any other animal species. Beetles are just a fragment of the Earth's biomass, the matter that makes up the Earth's living organisms. Insects alone-which comprise almost one million known species and perhaps millions yet to be discovered-create an amazing amount of biomass. The number of individual insects is about 10 quintillion (10,000,000,000,000,000,000). Insects probably have more biomass than any other type of land animal. In comparison, if the weight of the Earth's human population were added up, the biomass of the insect population would be 300 times as great. Biomass also refers to the organic material on Earth that has stored sunlight in the form of chemical energy. Biomass fuels, including wood, wood waste, straw, manure, sugar cane, and many other byproducts from a variety of agricultural processes, continue to be a major source of energy in much of the developing world. There are many who advocate the use of biomass for energy as it is readily available, whereas fossil fuels, such as petroleum, coal, or natural gas, take millions of years to form in the Earth and are finite and subject to depletion as they are consumed.

The American Heritage® Science Dictionary Copyright © 2011. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.

Cultural definitions for biomass


Material in growing or dead plants.

Notes for biomass

The term biomass is most often encountered in discussions of sources of energy, as biomass can be used to supply energy needs directly (as fuel wood, for example) or indirectly (by being converted to alcohol; see gasohol).

The New Dictionary of Cultural Literacy, Third Edition Copyright © 2005 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.