An infectious disease that is caused by the bacterium Yersinia pestis and is transmitted to humans from infected rats by the oriental rat flea. It is named for the characteristic feature of buboes (painfully enlarged lymph nodes) in the groin, armpits, neck, and elsewhere. Other symptoms of bubonic plague include headache, fever, chills, and weakness. Bubonic plague can lead to gangrene (tissue death) of the fingers, toes, and nose. Also called Black Death and Black Plague.
- Plague, Great
“Ther cam a privee theef men clepeth Deeth, / That in this contree al the peple sleeth, / And with his spere he smoot his herte atwo, / And wente his wey withouten wordes mo. / He hath a thousand slayn this pestilence.” “La Peste” (The Plague), a novel by the Nobel Prize-winning 20th- century […]
- Plague, sylvatic
A type of plague that is spread by ground squirrels and other wild rodents. Sylvatic plague is sometimes seen in the western portion of the US.
- Plan B
Brand name for a progestin-only emergency contraceptive designed to prevent pregnancy within 72 hours after a contraceptive accident or unprotected sex. However, early treatment is significantly more effective. Each 12 hours of delay in the start of treatment after intercourse generally reduces efficacy by 50%. Levonorgestrel, the active ingredient, is believed to act principally by […]
In practical optics, a surface that has been worked flat.
Flat. A lens that is planoconvex is flat on one side and convex on the other.