Wiktionary
n. (context musical instruments English) The elements of an electric guitar, mounted horizontally on legs, that uses a combination of a steel bar and pedals to vary the pitch
Wikipedia
The pedal steel guitar is a type of electric steel guitar that is built on legs or a stand and is fitted with foot pedals and knee levers which change the pitch of certain strings. Like other electric guitars, the musical instrument produces sound by the vibration of its strings which are converted by magnetic pickup connected to an amplifier.
Pedal steels may have one or two "necks" that typically have 10 strings each, but may have as many as 14. Unlike most other guitars, pedal steel guitars have reference lines on the fretboard where frets would be, but no actual frets. The player changes the pitch of one or more strings by sliding a metal bar (a steel) from one position to another or vibrating them with a mechanical device, while plucking the strings with the other hand. Pedal steels are typically plucked with a thumb pick and fingers, or two or three fingerpicks.
The distinctive feature of pedal steel guitars are the namesake pedals as well as knee levers. The pedals are mounted on a cross bar below the body and the knee levers extend from the bottom of the guitar's body and stretch or slacken the strings to change pitch as the guitar is played. The most common uses for the pedals and knee levers are raising the chord up a fourth without moving the bar, lowering the third of the chord to change the chord from a major to a minor, and lowering one of the root notes a whole step to produce a dominant seventh chord. Before the introduction of pedals on steel guitars these effects could only be created by carefully slanting the steel bar in the left hand.The action of the pedals may be fixed or may be configurable by the player to select which strings the pedals affect. While there are some fairly standard pedal assignments, many advanced players devise their own setups, called copedents. The range of copedents that can be set up varies considerably from guitar to guitar. Aftermarket modifications to make additional copedents possible are common.
The pedal steel evolved from the console steel guitar and lap steel guitar. Like the console steel, a pedal steel may have multiple necks.
The pedal steel, with its smooth portamenti, bending chords and complex riffs, is one of the most recognizable and characteristic instruments of American country music.