n. — Food, somewhat rare
the finest category of granulated sugar (see Image 1).
Type: 2. Preservation — Berry sugar is also called superfine granulated sugar, castor or caster sugar, fruit sugar or bar sugar (see the Canadian Sugar Institute reference).
The earliest attestation of berry sugar in Canada is from an English cookbook (see the 1910 quotation), which solidifies its classification as a preservation from BrE.
The term is most often used in the UK (see Chart 1), but has considerable frequency in Canada in relation to other non-UK locations (see Chart 2).
See also COD-2, s.v. "berry sugar", which is marked as "Cdn.".