In 1983, the metre was redefined in the International System of Units (SI) as the distance travelled by light in vacuum in 1/ 7008299792458000000â 299792458 of a second. As a result, the numerical value of c in metres per second is now fixed exactly by the definition of the metre.
Blattodea is an Order of insects containing the cockroaches. Cockroaches first evolved around 350-300 million years ago and are probably one of the most despised of all insects. For some people the mere mention of cockroaches will send them running for cover.
gutta-percha in Medicine. gutta-percha gutÂ·ta-perÂ·cha (gÅ­t'É-pÃ»r'chÉ) n. A rubbery substance from the latex of any of several tropical trees, used as a temporary filling material in dentistry and in the manufacture of orthopedic splints.