curb

1. (figurative) Something that checks or restrains; a restraint.Examples: "Even by theſe Men, Religion, that ſhould be / The curb, is made the ſpur to tyranny: / They with their double key of conſcience bind / The Subjects ſouls, and leave Kings unconfin'd; […]"; "The same also is that burning mention’d by S. Paul, whereof mariage ought to be the remedy; the Flesh hath other naturall and easie curbs which are in the power of any temperate man.."; "She maintains that the internet should face similar curbs to TV because young people are increasingly living online. "It's totally different, someone at Google watching the video from the comfort of their office in San Francisco to someone from a council house in London, where this video is happening right outside their front door.""USfiguratively

2. (equestrianism) A riding or driving bit for a horse that has rein action which amplifies the pressure in the mouth by leverage advantage placing pressure on the poll via the crown piece of the bridle and chin groove via a curb chain.Examples: "He that before ran in the pastures wild / Felt the stiff curb controul his angry jaws."; "Captain went out in the cab all the morning. Harry came in after school to feed me and give me water. In the afternoon I was put into the cab. Jerry took as much pains to see if the collar and bridle fitted comfortably, as if he had been John Manly over again. When the crupper was let out a hole or two, it all fitted well. There was no bearing rein—no curb—nothing but a plain ring snaffle. What a blessing that was!"Synonyms: curb bitUS

3. (Canada, US) A sidewalk, covered or partially enclosed, bordering the airport terminal road system with adjacent paved areas to permit vehicles to off-load or load passengers.CanadaUS