Ship Foot or Bruised Toenail is a condition where the toenail becomes bruise

Bruise

A bruise, also called a contusion, is a type of relatively minor hematoma of tissue in which capillaries and sometimes venules are damaged by trauma, allowing blood to seep into the surrounding interstitial tissues. Bruises can involve capillaries at the level of skin, subcutaneous tissue, muscle,...

d, usually as a result of a heavy impact such as from football or dropping something on the toe.

Etymology

The term is believed to have originated on warship

Warship

A warship is a ship that is built and primarily intended for combat. Warships are usually built in a completely different way from merchant ships. As well as being armed, warships are designed to withstand damage and are usually faster and more maneuvrable than merchant ships...

s during the Age of sail

Age of Sail

The Age of Sail was the period in which international trade and naval warfare were dominated by sailing ships, lasting from the 16th to the mid 19th century...

, where it was common for sailors to sustain such an injury from the impact of a recoiling cannon

Cannon

A cannon is any piece of artillery that uses gunpowder or other usually explosive-based propellents to launch a projectile. Cannon vary in caliber, range, mobility, rate of fire, angle of fire, and firepower; different forms of cannon combine and balance these attributes in varying degrees,...

. The condition in those days would have often been accompanied by other foot injuries, such as a fractured

Bone fracture

A bone fracture is a medical condition in which there is a break in the continuity of the bone...

toe.

Symptoms

Ship Foot is commonly diagnosed by a discolouration of the toenail, usually black, blue, purple or red. The syptoms are caused by trapped blood under the toenail. Blisters and cracked skin may also occur.