| permeability |
the quality or condition of permitting penetration or diffusion, as by a gas or liquid. |
| permeable |
of a substance, being such that gas or liquid can penetrate or diffuse through it. |
| permeate |
to pass or diffuse through; penetrate. [3 definitions] |
| Permian |
of, relating to, or designating the last geological period of the Paleozoic Era, from approximately 280 million to 220 million years ago, when reptiles became prominent, major mountain ranges such as the Appalachians formed, and great glaciers appeared in the Southern Hemisphere. [2 definitions] |
| permissible |
permitted; allowable. |
| permission |
the act of permitting. [2 definitions] |
| permissive |
allowing much, often excessive, freedom of behavior; lenient. [2 definitions] |
| permit |
to allow the entrance or the presence of. [5 definitions] |
| permutation |
the act, process, or result of change; transformation. [2 definitions] |
| permute |
to change the order of; alter the sequence of. [2 definitions] |
| pernicious |
having a very harmful or fatal effect; injurious, deadly, or destructive. |
| pernicious anemia |
a severe anemia in which red blood cells decrease in number and increase in size that is caused largely by a deficiency of vitamin B12. |
| pernickety |
variant of persnickety. |
| perorate |
to make a long speech or speak bombastically. [2 definitions] |
| peroration |
the concluding part of a speech in which there is a summing up of the principal points. [2 definitions] |
| peroxidase |
any of a group of enzymes that catalyzes the oxidation of various substances by a peroxide. |
| peroxide |
hydrogen peroxide. [3 definitions] |
| perpendicular |
at or forming a right angle to or with an intersecting line or plane. [7 definitions] |
| perpetrate |
to commit or carry out (a crime, act of mischief, or the like). [2 definitions] |
| perpetual |
lasting or continuing forever. [4 definitions] |
| perpetual motion |
the movement of a hypothetical device which, once put in motion, would operate indefinitely by creating its own energy in excess of that expended. |