What does plasma mean?
Plasma has two important meanings. In biology, it is the liquid portion of blood left after the blood cells have been removed. It carries proteins, nutrients, hormones, antibodies, and waste products, and its composition can provide valuable information about disease. In physics, plasma is a gas whose atoms have been ionized, meaning that some or all of their electrons have been separated from their nuclei. This state of matter is found in stars, lightning, auroras, fluorescent lamps, and many technological devices. The word therefore links the fluid world of living organisms with the energetic and electrically charged states of matter in the universe. Although plasma is often used informally for the liquid part of blood, the scientific distinction between plasma and serum is important: plasma is obtained from unclotted blood, while serum is the liquid left after clotting.
The fluid component of blood, containing water, proteins, salts, hormones, and other substances but no blood cells.
"The test uses a sample of plasma to detect antibodies."
This biological sense is distinct from serum, which is obtained after blood has clotted.
A gas in which atoms are ionized, so that the substance contains free electrons and charged ions and conducts electricity.
"The spacecraft's heat shield is designed to withstand the extreme heat generated when it passes through plasma."
In physics and engineering, plasma commonly refers to an ionized gas or a state of matter involving ionized material.
The plural is used when referring to separate samples of blood plasma or distinct plasmas in scientific contexts.
"The researchers compared blood plasmas collected from two groups of participants."
From the Greek word for something molded, plasma gives both blood and stars their shimmering character.
Reviewed by Deb Chak, Editor. AI-assisted content curated by RJS Tech Solutions LLP.
Where does plasma come from?
The word comes through Latin from Greek plásma, meaning “something molded” or “a molded thing,” related to the Greek verb plássein, “to mold.” Scientific usage developed through modern biology and physics, where the word was applied first to the fluid portion of blood and later to ionized gases. Its connection with molding underlies related English forms such as plastic and plasmatic.
Related word forms
How plasma is actually used
In medicine and biology, the term normally refers to blood plasma and is distinct from serum. In physics and engineering, it denotes an ionized gas; the spelling is also used attributively in terms such as plasma display.
Easily confused with plasma
Serum is the liquid that remains after blood has clotted, whereas plasma is the liquid remaining after the cells are removed from unclotted blood.