'Double first' definitions:

Definition of 'double first'

(from WordNet)
noun
A first-class honours degree in two subjects

Definition of 'Double first'

From: GCIDE
  • Double first \Dou"ble first`\ (Eng. Universities) (a) A degree of the first class both in classics and mathematics. (b) One who gains at examinations the highest honor both in the classics and the mathematics. --Beaconsfield. [1913 Webster]