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annual rings

(Encyclopedia)annual rings, the growth layers of wood that are produced each year in the stems and roots of trees and shrubs. In climates with well-marked alternations of seasons (either cold and warm or wet and dr...

nitrous oxide

(Encyclopedia)nitrous oxide or nitrogen (I) oxide, chemical compound, N2O, a colorless gas with a sweetish taste and odor. Its density is 1.977 grams per liter at STP. It is soluble in water, alcohol, ether, and ot...

parcel post

(Encyclopedia)parcel post, sending of packages through the mail service. At the congress of the Universal Postal Union in Paris in 1878, an international parcel-post system was established. The British parcel-post ...

avocet

(Encyclopedia)avocet ăvˈəsĕt [key], common name for a long-legged wading bird about 15 to 18 in. (37.5–45 cm) long, related to the snipe and belonging to the same family as the stilt. The American avocet or b...

pipit

(Encyclopedia)pipit, common name for a group of chiefly Eurasian and African birds that together with the wagtails constitute a subfamily of songbirds related to the Old World warblers and thrushes. Pipits are trim...

Tagus

(Encyclopedia)Tagus tāˈgəs [key], Span. Tajo, Port. Tejo, river, c.585 mi (940 km) long, rising in the mountains E of Madrid, E Spain, and draining the central part of the Iberian Peninsula. The Tagus flows nort...

rudder

(Encyclopedia)rudder, mechanism for steering an airplane or a ship. In ships it is a flat-surfaced structure hinged to the stern and controlled by a helm. When the ship is on a straight course, the rudder is in lin...

speedometer

(Encyclopedia)speedometer, instrument that indicates speed. A cable from an automotive speedometer is attached to the rear of the transmission of an automobile; the cable turns at a rate proportional to the speed o...

sodium hydroxide

(Encyclopedia)sodium hydroxide, chemical compound, NaOH, a white crystalline substance that readily absorbs carbon dioxide and moisture from the air. It is very soluble in water, alcohol, and glycerin. It is a caus...

sodium silicate

(Encyclopedia)sodium silicate, any one of several compounds containing sodium oxide, Na2O, and silica, Si2O, or a mixture of sodium silicates. Sodium orthosilicate is Na4SiO4 (or 2Na2O·SiO2); sodium metasilicate i...