Columbia Encyclopedia

(Encyclopedia) pheromones, any of a variety of substances, secreted by many animal species, that alter the behavior of individuals of the same species. Sex attractant pheromones, secreted by a male or female to attr...

(Encyclopedia) disk plow or disk, farm implement employing a row or rows of concave circular steel disks that cut and pitch the soil in a way somewhat similar to a moldboard plow. It can be used in many situations w...

(Encyclopedia) breakwater, offshore structure to protect a harbor from wave energy or deflect currents. When it also serves as a pier, it is called a quay; when covered by a roadway it is called a mole. In the Unite...

(Encyclopedia) circumpolar star, star whose diurnal circle lies completely above or completely below an observer's horizon. A star whose diurnal circle lies above the horizon never sets, even though it cannot be see...

(Encyclopedia) Honorius I hōnôrˈēəs [key], pope (625–38), an Italian; successor of Boniface V. He showed great interest in the church in Spain and the British Isles, and he did a great deal to reform the educ...

(Encyclopedia) identity theft, the use of one person's personal information by another to commit fraud or other crimes. The most common forms of identity theft occur when someone obtains another person's social secu...

(Encyclopedia) infectious canine hepatitis, acute viral disease of canines, especially dogs and foxes. The causative agent, an adenovirus, is not infectious to humans. In foxes the disease is manifested primarily as...

(Encyclopedia) conjunction, in astronomy, alignment of two celestial bodies as seen from the earth. Conjunction of the moon and the planets is often determined by reference to the sun. When a body is in conjunction ...

(Encyclopedia) cover crop, green temporary crop grown to prevent or reduce erosion and to improve the soil by building up its organic content. Green-manure crops, which are specifically grown for their organic conte...

(Encyclopedia) Kyffhäuser kĭfˈhoizər [key], forested mountain, c.1,550 ft (470 m), Saxony-Anhalt, central Germany. It is crowned by the two ruined castles of Rothenburg (7th cent.) and Kyffhausen (12th cent.) an...