-eshən noun
( -s )
Etymology: New Latin praecession-, praecessio, from Medieval Latin, action of preceding, from Latin praecessus (past participle of praecedere to precede) + -ion-, -io -ion — more at precede
: a comparatively slow gyration of the rotation axis of a spinning body (as a top) about another line intersecting it so as to describe a cone caused by the application of a torque tending to change the direction of the rotation axis and being a motion continuously at right angles to the plane of the torque producing it