What is the meaning of Martingale?

A piece of harness used on a horse to keep it from raising its head above a desired point.

A spar, or piece of rigging that strengthens the bowsprit.

A stochastic process for which the conditional expectation of future values given the sequence of all prior values is equal to the current value.

A gambling strategy in which one doubles the stake after each loss.

A strap attached to the sword handle, preventing a sword being dropped if disarmed.

To employ the martingale strategy in gambling.

martingale

plural of martingala

Source: wiktionary.org