chromosome

American  

[kroh-muh-sohm] / ˈkroʊ məˌsoʊm /

noun

Genetics.

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

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

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:

• chromatin vs. chromosome
• chromosome vs. chromatid
• 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

During his first appointment in Seattle, my parents learned that their seven-year-old’s illness was accompanied by the Philadelphia chromosome.

From The Wall Street Journal • May 5, 2026

The results showed that segments of the Y chromosome matched across the participants.

From Science Daily • May 4, 2026

Prader-Willi syndrome stems from the loss of function of specific genes on the paternal copy of chromosome 15.

From Barron's • Apr. 6, 2026

"While the direct evidence of physical advantage in transgender people is pretty strong, the evidence of advantage for those with DSD, even though they have a Y chromosome, is highly disputed."

From BBC • Mar. 31, 2026

Research into HPV eventually uncovered how Henrietta’s cancer started: HPV inserted its DNA into the long arm of her eleventh chromosome and essentially turned off her p 5 3 tumor suppressor gene.

From "The Immortal Life of Henrietta Lacks" by Rebecca Skloot