1. A strap or device attached to a horse's harness that prevents the animal from raising its head too high.
Usage: equestrian; also spelled 'martingale'
2. In mathematics and probability, a sequence of random variables with the property that the expected value of the next term equals the current term.
Usage: technical; mathematics

Examples

• The rider adjusted the martingal to keep the horse's head at the proper angle.
• A standing martingal is commonly used in English riding disciplines.
• The martingal prevents the horse from tossing its head during competition.
• In probability theory, a martingal is an important concept for modeling fair games.
• The mathematician proved that the sequence formed a martingal under the given conditions.