fatty

Etymology 1

From Middle English fatty, equivalent to fat + -y. Cognate with Saterland Frisian fattig (“fatty”), Dutch vettig (“fatty, greasy”), German Low German fettig (“fatty”), German fettig (“fatty”).

adj

1. Containing, composed of, or consisting of fat.
   That means eating fruits and vegetables and cutting back on fatty foods. 2002, George W. Bush, Presidential Radio Address - June 22
   As we age, the major arteries of our bodies frequently become thickened with plaque, a fatty material with an oatmeal-like consistency that builds up along the inner lining of blood vessels. 2013 July-August, Stephen P. Lownie, David M. Pelz, “Stents to Prevent Stroke”, in American Scientist
2. Like fat; greasy.
   1849, Hippocrates (Translated by Francis Bacon), Of the Epidemics, Book II, Section 1. On the sixth, stools black, fatty, viscid, fetid; slept, more collected.
3. (slang) Literally or figuratively large.
   Be careful of the taxi drivers out there though, I've heard they sell you drugs, drop you off at your hotel and then dob you in to the Thai Police to get a fatty reward! 2007, getting rid of weed smell tips
   Instead of going my normal route (ordering the book through the store, checking it out in person, and then ordering it online so I could get a fatty discount) I impulsively bought the book. 2007, A. Bryant, Disappointment to Say the Least
   I'm trying to get a fatty project done in a couple of hours right now. 2007, Rimma http://comments.deviantart.com/4/718221/456809541

Etymology 2

From fat + -y (diminutive suffix).

noun

1. (derogatory, slang) An obese person.
   It's hardly surprising, when it has to support that enormous gut! Lose some weight, fatty!
2. (slang) A large marijuana cigar; a blunt.
   We went to Plaster Creek, smoked a fattie, and emerged doing somersaults and cartwheels and laughing. 2004, Anthony Kiedis, Larry Sloman, Scar Tissue