umbraced used when the arm is completely covered with armour (see vambraced)
umbrated or adumbrated shadowed
undé a line of partition formed like waves (see ondé and wavy)
unguled used of animals hooves when they are coloured differently from the body
urchin a hedgehog
uriant used of a fish when shown with the head downwards and the tail erect
urvant or urved turned or bowed upwards