What does vitellus mean?
Vitellus is a formal biological term for the yolk of an egg, particularly the nutrient-bearing material stored in a bird's egg. In embryological description, it names the yolk from which a developing embryo draws nourishment before it can feed independently. The word is uncommon in ordinary conversation but precise in technical and historical writing, where it can distinguish the yolk itself from the surrounding albumen, shell, or membranes. A sentence such as “The embryo was sustained by the vitellus” therefore signals a scientific or antiquarian register rather than everyday speech. Although usually encountered in zoology, embryology, and historical descriptions of eggs, vitellus comes from Latin and belongs to a wider family of yolk-related terms including vitelline and vitellin. Its usefulness lies in giving a single exact term to a familiar substance when discussing its composition, function, or developmental role, especially where a general word such as “yolk” might be too broad or conversational.
nounThe yolk of an egg, especially the nutrient-bearing material from which an embryo draws nourishment. The term is chiefly used in biology, embryology, and historical or descriptive writing.
- The yolk of an egg, particularly the portion that provides nourishment to a developing embryo.
"The developing embryo was sustained by the vitellus until it hatched."
"Each embryo is nourished by the vitellus during its development inside the egg."
"The archive notes describe the preserved vitellus as unusually dark."
The learned plural vitelli is standard, following the Latin form.
"The three vitelli were separated for analysis."
Say “yolk” at breakfast and “vitellus” in a biology lab.
Reviewed by Deb Chak, Editor. AI-assisted content curated by RJS Tech Solutions LLP.
Etymology of vitellus
Vitellus was borrowed from Latin vitellus, meaning “the yolk of an egg.” The Latin word is a diminutive of vitulus, “calf,” and the English borrowing appeared in early modern scientific usage. English later developed vitelline and vitellin from the same Latin base.
Related word forms
How vitellus is actually used
Chiefly formal or technical, especially in biology, embryology, and historical descriptions of eggs. It is uncommon in everyday conversation.
Easily confused with vitellus
Vitellus is the noun naming an egg's yolk, while vitelline is an adjective meaning relating to or derived from the yolk, as in vitelline membrane.
A vitellus is the yolk of an egg, whereas a villus is a slender projection found in the lining of the intestine or certain other organs.