Definition of PLACOID. : of, relating to, or being a scale of dermal origin with an enamel-tipped spine characteristic of the elasmobranchs. ADVERTISEMENT.Greek plak-, plax flat surface.First Known Use: 1842.efinition of PLACOID. : of, relating to, or being a scale of dermal origin with an enamel-tipped spine characteristic of the elasmobranchs. ADVERTISEMENT. Greek plak-, plax flat surface. First Known Use: 1842.
A tree pruner is a class 1 lever. The fulcrum is where the two blades cross, and the load is what you are cutting. The effort is applied to the two handles.
Cork is the bark of a quercus suber, or cork oak. A tree grows for approx. 25 years then is stripped of its bark from lower parts of the tree. It re-grows and is strippeâ¦d every 9 years until 250 years old or more. It is used for wine corks, flooring, gaskets, coasters, construction, etc.