Rook
From Battlestar Wiki, the free, open content Battlestar Galactica encyclopedia and episode guide
A "rook'" (ostensibly a contraction of "rookie") applies to a nugget who has completed their Viper flight training and qualifications, yet is still inexperienced in actual combat.
Ensigns Brent Baxton and Joseph Clark are rooks that completed their training on the flight simulators available on Pegasus and are assigned to Galactica afterwards (Scar).