What is the meaning of convertible?

noun

• A car that has top that can be folded or removed.
• A corporate security (usually bonds or preferred stock) that can be exchanged for another form of security (usually common stock.
  • synonyms: convertible security
• A sofa that can be converted into a bed.
  • synonyms: sofa bed

adjective

• Capable of being exchanged for or replaced by something of equal value.
  • usage: "convertible securities"
  • synonyms: exchangeable
• Designed to be changed from one use or form to another.
  • usage: "a convertible sofa"; "a convertible coupe"
• Capable of being changed in substance as if by alchemy.
  • usage: "is lead really transmutable into gold"; "ideas translatable into reality"
  • synonyms: transformable, translatable, transmutable