What does diploid mean?
"Diploid" is a term from genetics describing a cell or organism that contains two complete sets of chromosomes — one set inherited from each parent. In humans, for example, all body cells except eggs and sperm are diploid, carrying 46 chromosomes organised into 23 pairs, while the reproductive cells carry only a single set and are described as haploid. The word is chiefly used as an adjective, though biologists may also use it as a noun to refer to a diploid cell or organism, or to the diploid stage of an alternating life cycle, common in plants. Derived from the Greek "diplous", meaning double, it is a technical but widely understood term in biology education and research. Understanding "diploid" helps clarify how sexual reproduction preserves chromosome numbers across generations: fertilisation restores the doubled state by fusing two haploid gametes. It is a precise, neutral term with no figurative or colloquial use, appearing almost exclusively in scientific contexts.
(Of a cell or nucleus) containing two complete sets of chromosomes, one inherited from each parent; denoting the condition of having two homologous copies of each chromosome.
"The zygote formed at fertilisation is diploid, restoring the chromosome number lost during meiosis."
A diploid cell or organism; the diploid phase in the life cycle of an organism that alternates between haploid and diploid stages.
"In mosses, the haploid gametophyte is the dominant stage, while the diploid exists briefly as the sporophyte."
As a noun, "diploid" is used mainly in genetics and botany, often in phrases like "the diploid" referring to the diploid generation or phase of a life cycle.
Used when referring to multiple diploid organisms or cells collectively, particularly in genetics and breeding literature.
"Crossing diploids with tetraploids can produce sterile triploid offspring."
Every cell in your body carries two full sets of chromosomes — one from your mother, one from your father — and 'diploid' is the word that captures that genetic doubling.
Reviewed by Deb Chak, Editor. AI-assisted content curated by RJS Tech Solutions LLP.
Etymology of diploid
"Diploid" derives from the Greek "diplous", meaning double or twofold, combined with the suffix "-oid", indicating likeness or form. It entered English scientific usage in the early twentieth century alongside related terms such as "haploid" and "polyploid", which share the same "-ploid" combining element. Its Greek root also appears in words like "diplopia" (double vision) and "diploma", both ultimately tracing back to the same notion of doubleness.
How diploid is actually used
"Diploid" is primarily a technical term used in genetics, cytology, botany, and zoology. It is rarely encountered outside scientific writing, though it occasionally appears in science journalism and biology education. It is neutral in connotation and has no informal register. When used as a noun, it typically refers to an organism or cell that is diploid, or to the diploid phase of a life cycle.
Easily confused with diploid
Haploid describes cells with a single set of chromosomes (such as gametes), whereas diploid describes cells with two complete sets — one from each parent.