- noun a hard top layer
- noun the top layer of the surface of the earth, which is formed of rock and lies above the asthenosphere
- noun a hard layer which forms on the surface of something, e.g. the crust of salts formed on soil after evaporation
- The outermost solid layer of the Earth, or of similar solid planets
- The outer hard golden brown surface of bread or cakes or other mixtures which are baked or fried
- The pastry top on a filled sweet or savoury pie or dish not necessarily having a pastry base
- noun (one’s) head. This London working-class usage is almost always heard in the forms off one’s crust or do one’s crust.
- noun the hard outer part of a loaf of bread or of a roll or of a slice of bread
- a crystalline sediment that forms inside bottles containing red wine or port during long bottle-ageing
Origin & History of “crust”
Latin crusta meant ‘hard outer covering, shell’ (it is related to a number of words, including ultimately crystal, denoting a hard surface caused by freezing). Old French acquired it as crouste (the modern French form croûte formed the basis of croûton, borrowed into English in the early 19th century), and passed it on to middle English as cruste. Crusta formed the basis of the modern Latin adjective crustāceus ‘having a shell’, applied in the early 19th century to the crustacea or crustaceans. And a custard was originally a kind of pie enclosed in a crust.