A funnel of cloth, paper, etc., usually fitted with a nozzle, through which pastry, icing, or other food of a similar consistency may be piped, especially in order to decorate a cake, etc.
Origin
1930s; earliest use found in The Times.
Definition of piping bag in US English:
piping bag
noun
A funnel of cloth, paper, etc., usually fitted with a nozzle, through which pastry, icing, or other food of a similar consistency may be piped, especially in order to decorate a cake, etc.