| ozone layer |
an atmospheric layer between ten and twenty miles above the earth that contains a substantial concentration of ozone, which absorbs ultraviolet radiation from space and prevents some heat loss from the earth; ozonosphere. |
| ozonize |
to treat, combine, or saturate with ozone. [2 definitions] |
| ozonosphere |
see "ozone layer." |
| P1 |
abbreviation of "passing," completed successfully. |
| P2 |
symbol of the chemical element phosphorus. |
| P- |
in the U.S. military, a pursuit plane, such as a P-38 or P-40. |
| p |
the sixteenth letter of the English alphabet. [3 definitions] |
| p. |
abbreviation of "page," one side of a sheet of printed or written paper. [2 definitions] |
| PA1 |
abbreviation of "Pennsylvania," an eastern U.S. state south of New York. |
| Pa |
symbol of the chemical element protactinium. |
| PA2 |
abbreviation of "public address." |
| pa |
(informal) father; papa. |
| pa'anga |
the chief monetary unit of Tonga, equaling one hundred seniti. |
| Pablo Picasso |
a Spanish painter and sculptor (b.1881--d.1973). |
| Pablum |
trademark for a smooth, bland baby cereal. [2 definitions] |
| pabulum |
a soft substance that serves to nourish. [2 definitions] |
| PAC |
abbreviation of "political action committee." |
| pac |
an insulated, waterproof boot designed for wear in extreme cold. [3 definitions] |
| pace1 |
the length of one stride in walking. [12 definitions] |
| pace2 |
with the permission of (used to disagree politely). |
| pacemaker |
a small electronic device implanted under the skin to regulate the heart rate in patients with heart problems. [3 definitions] |