chromosome

American  

[kroh-muh-sohm] / ˈkroʊ məˌsoʊm /

noun

Genetics.

• chromosomes
  plural

1. any of several threadlike bodies, consisting of chromatin, that carry the genes in a linear order: the human species has 23 pairs, designated 1 to 22 in order of decreasing size and X and Y for the sex-determining chromosomes.

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chromosome British  

/ ˈkrəʊməˌsəʊm /

noun

1. any of the microscopic rod-shaped structures that appear in a cell nucleus during cell division, consisting of nucleoprotein arranged into units (genes) that are responsible for the transmission of hereditary characteristics See also homologous chromosomes

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chromosome Scientific  

/ krō′mə-sōm′ /

1. A structure in all living cells that consists of a single molecule of DNA bonded to various proteins and that carries the genes determining heredity. In all eukaryotic cells, the chromosomes occur as threadlike strands in the nucleus. During cell reproduction, these strands coil up and condense into much thicker structures that are easily viewed under a microscope. Chromosomes occur in pairs in all of the cells of eukaryotes except the reproductive cells, which have one of each chromosome, and some red blood cells (such as those of mammals) that expel their nuclei. In bacterial cells and other prokaryotes, which have no nucleus, the chromosome is a circular strand of DNA located in the cytoplasm.

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Other Word Forms

Derived Forms

• chromosomal
  adjective
• interchromosomal
  adjective
• nonchromosomal
  adjective
• chromosomally
  adverb
• interchromosomally
  adverb

Inflected Forms

Nouns

• chromosomes
  plural

Etymology

Origin of chromosome

First recorded in 1885–90; chromo- + -some ³

Compare meaning

How does chromosome compare to similar and commonly confused words? Explore the most common comparisons:

• chromosome vs. chromatid
• chromatin vs. chromosome
• plasmid vs. chromosome

Explanation

A chromosome is a strand of DNA that is encoded with genes. In most cells, humans have 22 pairs of these chromosomes plus the two sex chromosomes (XX in females and XY in males) for a total of 46. The word chromosome was originally coined in German from the Greek words khroma, meaning "color," and soma meaning "body." In the late 1800s, a scientist, Wilhelm von Waldeyer-Hartz, gave chromosomes their name because chromosomes easily accept dye and take on patterns of light and dark when exposed to different stains that help identify the different chromosomes.

Example Sentences

See Examples For:

chromosome chromosomes

The Year 8 student from Western Australia has Down Syndrome – a genetic condition caused by an extra copy of chromosome 21 which leads to physical and intellectual disabilities.

From BBC ● Aug. 12, 2026

Down's syndrome is when you're born with an extra chromosome - and people with the condition are likely to have some level of learning disability.

From BBC ● Jul. 26, 2026

In such a scheme, Neanderthal DNA can be transmitted widely through the ordinary chromosomes, while the Neanderthal X chromosome circulates less easily, since a father passes it on only to his daughters.

From Science Daily ● Jul. 7, 2026

This is why the sex chromosomes, and the X chromosome in particular, can eliminate DNA from the other group more quickly.

From Science Daily ● Jul. 7, 2026

Without their knowing, my grandparents, on their way to America, were each carrying a single mutated gene on the fifth chromosome.

From "Middlesex: A Novel" by Jeffrey Eugenides

Telomeres help keep chromosomes from deteriorating or being incorrectly identified by cells as broken pieces of DNA.

From Science Daily ● Aug. 2, 2026

The study, published in Science Advances, found that TRF2 does much more than shield chromosomes.

From Science Daily ● Aug. 2, 2026

Many characteristics go into determining someone’s sex: chromosomes, reproductive organs, hormonal balances, secondary sex characteristics like breast tissue and body-hair distribution.

From Slate ● Jul. 7, 2026

The condition “may involve chromosomes, hormones, reproductive organs or genitals.”

From Los Angeles Times ● Jul. 7, 2026

At this time the chromosomes do not split, but one whole chromosome of each pair goes into each daughter cell.

From "Silent Spring" by Rachel Carson