Definition of trussing:
(n) :
(architecture, engineering) The timbers, etc., that form a truss.
(n) :
The art of stiffening or bracing a set of timbers, etc., by putting in struts, ties, etc., until it has something of the character of a truss.
(adj) :
(heraldry, of a bird) In the act of seizing (something).
(n) :
(obsolete) The act of a hawk or other bird of prey in seizing its quarry and soaring into the air with it.