deorsum- +

(Latin: downward, downwards)

deorsum
A turning down.
deorsumduction
Rotation of one eye downward.
deorsumvergence; infravergence
Disjunctive reciprocal movement of the eyes in which one eye rotates downward while the other one remains still.
deorsumversion
1. A turning down.
2. The downward deviation of one eye.