loaf

Etymology 1

* From Middle English lof, laf, from Old English hlāf (“bread, loaf of bread”), from Proto-West Germanic *hlaib, from Proto-Germanic *hlaibaz (“bread, loaf”), of uncertain origin. Perhaps related to Old English hlifian (“to stand out prominently, tower up”). Cognate with Scots laif (“loaf”), German Laib (“loaf”), Swedish lev (“loaf”), Russian хлеб (xleb, “bread, loaf”), Polish chleb (“bread”). * (brain or head): Rhyming slang, shortened from "loaf of bread".

noun

1. (also loaf of bread) A block of bread after baking.
   Philander went into the next room[…]and came back with a salt mackerel that dripped brine like a rainstorm. Then he put the coffee pot on the stove and rummaged out a loaf of dry bread and some hardtack. 1913, Joseph C. Lincoln, chapter 8, in Mr. Pratt's Patients
2. Any solid block of food, such as meat or sugar.
3. (Cockney rhyming slang) The brain or the head (mainly in the phrase use one's loaf).
4. A solid block of soap, from which standard bar soap is cut.

verb

1. (Cockney rhyming slang) To headbutt
2. (Internet slang) To be in catloaf position (for cats or other animals)

Etymology 2

Probably a back-formation from loafer.

verb

1. (intransitive) To do nothing, to be idle.
   loaf about, loaf around .
   2015, Elizabeth Royte, Vultures Are Revolting. Here’s Why We Need to Save Them., National Geographic (December 2015)http://ngm.nationalgeographic.com/2016/01/vultures-text They don’t (often) kill other animals, they probably form monogamous pairs, and we know they share parental care of chicks, and loaf and bathe in large, congenial groups.