Many authors have incorrectly assumed that the 'C' in "C-value" refers to "characteristic", "content", or "complement". Even among authors who have attempted to trace the origin of the term, there had been some confusion because Hewson Swift did not define it explicitly when he coined it in 1950.<ref name="Swift1950">{{cite journal |author=Swift H |year=1950 |title=The constancy of deoxyribose nucleic acid in plant nuclei |journal=Proceedings of the National Academy of Sciences of the USA |volume=36 |issue=11 |pages=643–654|pmid=14808154 |pmc=1063260 |doi=10.1073/pnas.36.11.643|bibcode=1950PNAS...36..643S |doi-access=free }}</ref> In his original paper, Swift appeared to use the designation "1C value", "2C value", etc., in reference to "classes" of DNA content (e.g., Gregory 2001,<ref name="Gregory2001">{{cite journal |author=Gregory TR |year=2001 |title=Coincidence, coevolution, or causation? DNA content, cell size, and the C-value enigma |journal=Biological Reviews |volume=76 | doi = 10.1017/S1464793100005595 | pmid=11325054 |issue=1 |pages=65–101 |doiarticle-broken-datenumber=15 April 2025S1464793100005595 }}</ref> 2002<ref name="Gregory2002">{{cite journal |author=Gregory TR |year=2002 |title=A bird's-eye view of the C-value enigma: genome size, cell size, and metabolic rate in the class Aves |journal=Evolution |volume=56 |pmid=11913657 |issue=1 |pages=121–30 |doi=10.1111/j.0014-3820.2002.tb00854.x|doi-access=free }}</ref>); however, Swift explained in personal correspondence to Prof. Michael D. Bennett in 1975 that "I am afraid the letter C stood for nothing more glamorous than 'constant', i.e., the amount of DNA that was characteristic of a particular [[genotype]]" (quoted in Bennett and Leitch 2005<ref name="Bennett2005">{{cite book |vauthors=Bennett MD, Leitch IJ |year=2005 |chapter=Genome size evolution in plants |title=The Evolution of the Genome |editor=T.R. Gregory |pages=89–162 |publisher=Elsevier |___location=San Diego|title-link=The Evolution of the Genome }}</ref>). This is in reference to the report in 1948 by Vendrely and Vendrely of a "remarkable constancy in the nuclear DNA content of all the cells in all the individuals within a given animal species" (translated from the original [[French language|French]]).<ref name="Vendrely1948">{{cite journal |author=Vendrely R, Vendrely C |year=1948 |title=La teneur du noyau cellulaire en acide désoxyribonucléique à travers les organes, les individus et les espèces animales : Techniques et premiers résultats |journal=Experientia |volume=4 |issue=11 |pages=434–436 |language=French|pmid=18098821 |last2=Vendrely |doi=10.1007/bf02144998|s2cid=22272730 }}</ref> Swift's study of this topic related specifically to variation (or lack thereof) among [[chromosome]] sets in different cell types within individuals, but his notation evolved into "C-value" in reference to the haploid DNA content of individual species and retains this usage today.
