What does fatty mean?
'Fatty' functions chiefly as an adjective describing anything that contains or consists largely of fat — fatty meats, fatty foods, fatty acids, and fatty tissue are all standard expressions in cooking, nutrition, and medicine. In these scientific and everyday uses the word carries no judgment; it simply signals high fat content. The word also exists as an informal noun meaning a fat person, a use dating back centuries but now widely regarded as offensive and demeaning, so it should be avoided in respectful conversation. Derived forms include the noun 'fattiness', describing the degree to which something tastes or is rich in fat, most often used of food and wine. Formed simply by adding the suffix '-y' to 'fat', the word is transparent yet remarkably versatile, appearing everywhere from chemistry classrooms to dietary guidelines. Its dual character — clinical on one hand, cruel on the other — makes context the key to using it well.
Containing, consisting of, or relating to a large amount of fat.
"A diet high in fatty meats can raise cholesterol levels."
Standard and neutral in nutritional and medical writing.
(Informal) A person who is fat.
"The school ran workshops on the harm caused by name-calling like 'fatty'."
Derogatory; generally considered offensive when applied to people.
Applies only to the informal noun sense referring to people; this plural inherits the noun's derogatory connotation and is best avoided entirely.
"The old playground taunt used the plural 'fatties' to mock classmates."
Every cell in your body is wrapped in a membrane made of fatty molecules — without fat, you would quite literally fall apart.
Reviewed by Deb Chak, Editor. AI-assisted content curated by RJS Tech Solutions LLP.
Etymology of fatty
The word 'fatty' is formed from 'fat', an ancient English word traceable to Old English 'fǣtt', meaning 'fat' or 'fatted'. The suffix '-y', which turns nouns into adjectives meaning 'characterized by' or 'full of', was appended to create 'fatty', first appearing in English in the early modern period. Because 'fat' is a native Germanic word rather than a Latin or French borrowing, its true cognates lie in other Germanic languages, such as German 'feist' and Dutch 'vet', which stem from the same ancestral root.
Related word forms
How fatty is actually used
As an adjective, 'fatty' is neutral and common in medical and nutritional contexts (e.g. fatty acids, fatty tissue). When used as a noun for a person, it is informal and widely considered insulting; avoid it in polite or professional speech.
Easily confused with fatty
'Fat' refers to the substance itself or a person carrying excess weight, while 'fatty' describes something that contains a lot of fat (or, as slang, names a fat person).