n. — Food
icing sugar.
Type: 2. Preservation — Confectioners sugar is another name for what is more commonly known as icing sugar or powdered sugar. Icing sugar is not Canadian, despite earlier claims (see entry), while confectioners' sugar, now often without the apostrophe, is a British preservation. Chart 1 shows that today the term is most common in Canada, followed by the UK. Chart 2 shows that another variant, powdered sugar, is common in Commonwealth countries, but of limited use in the US.
See also: berry sugar icing sugar icing ((3))
- Confectioners sugar (icing sugar) is finely granulated sugar with added cornstarch (see Canadian Sugar Institute reference).
Images:

Chart 1: Internet Domain Search, 4 Jul. 2014 
Chart 2: Internet Domain Search, 26 Nov. 2015