Ge-þinnian

According to the Old English Dictionary:

-þinngian, -þynnian;

ge-þinnian

p. ode; pp. od To thin, lessen, diminish, dispel; attenuāre :-- Ic hie sceal ǽrest geþinnian [geþinngian, MS. Bod.] I must first dispel them, Bt. 5, 3; Fox 14, 19. ge-þinnian