the ordering of genes in a haploid set of chromosomes of a particular organism; the full DNA sequence of an organism
"the human genome contains approximately three billion chemical base pairs"
The complete genetic information (either DNA or, in some viruses, RNA) of an organism.
"The human genome contains all the genetic instructions needed to build and maintain a person's body."
In plain English: A genome is all of the genetic instructions found inside an organism's cells that tell it how to grow and function.
"Scientists sequenced the human genome to better understand genetic diseases."
Usage: Use genome to refer specifically to the entire set of hereditary material within one cell or chromosome pair, rather than a single gene. This term applies universally to all organisms, including those that use RNA instead of DNA as their genetic code.
The word genome comes from German, where botanist Hans Winkler coined it in 1920 by blending "gene" and "chromosome." The spelling was later adjusted to match the pattern seen in similar words like chromosome.