convertible

Concise Oxford English Dictionary © 2008 Oxford University Press:
convertible/kənˈvɜːtəbl/

▶adjective

• 1 able to be converted.

  ■ (of currency) able to be converted, especially into gold or US dollars.

  ■ (of a bond or stock) able to be converted into ordinary or preference shares.

• 2 (of a car) having a folding or detachable roof.

• 3 Logic (of terms) synonymous.

▶noun

• 1 a convertible car.

• 2 a convertible bond or stock.

– derivatives
convertibility noun.