Secondary use
Black's Law Dictionary · Henry Campbell Black, M.A. · 1910
Black's Law Dictionary
A use limited to take effect in derogation of a preceding estate, otherwise called a "shifting use," as a conveyance to the use of A. and his heirs, with a proviso that, when B. returns from India, then to the use of C. and his heirs.
1 Steph. Comm. 546.