a flat bar on a machine such as a bicycle, car, etc. that you push down with your foot in order to make parts of the machine move or work （自行车、汽车等的）脚蹬子，踏板 
I couldn't reach the pedals on her bike. 我骑她的车够不到脚蹬子。 She pressed her foot down sharply on the brake pedal. 她猛踩刹车踏板。 a pedal boat (= one driven by pedals) 用脚踏驱动的船。
Extra ExamplesTopics Transport by car or lorryc1Her foot was working the pedal of the sewing machine. 她用脚蹬着缝纫机的踏板。 To stop the machine push the foot pedal. 踩脚踏板可以让机器停止运转。
Oxford Collocations Dictionaryadjective- accelerator
- brake
- clutch
- …
- depress
- press
- push
- …
- control something
- operate something
- boat
- car
- cycle
- …
- on a/the pedal
a bar on a musical instrument such as a piano or an organ that you push with your foot in order to control the sound （钢琴、风琴等的）踏板，踏瓣，脚踏键 
The soft pedal is placed leftmost in the row of pedals. 软踏板放在踏板排的最左边。 Some guitar players tend to overuse the wah-wah pedal. 一些吉他手往往会滥用“哇哇”踏板。
Oxford Collocations Dictionaryadjective- accelerator
- brake
- clutch
- …
- depress
- press
- push
- …
- control something
- operate something
- boat
- car
- cycle
- …
- on a/the pedal
Word Originearly 17th cent. (denoting a foot-operated lever of an organ): from French pédale, from Italian pedale, from Latin pedalis ‘a foot in length’, from pes, ped- ‘foot’.
Idioms
put the pedal to the metal
(also with the pedal to the metal)
(North American English, informal)(to go) at full speed; (to drive) with the accelerator of the car pressed to the floor 全速（前进）；（开车时）将油门踩到底 We drove through the night flat-out, with the pedal to the metal. 我们将油门踩到底，在夜色里全速前进。
to use as much effort as possible; with as much effort as possible 竭尽全力；尽最大努力 I'm still putting the pedal to the metal here at work. 我还在这里竭尽全力地工作。