Source : Webster's Revised Unabridged Dictionary (1913)

Convertible \Con*vert"i*ble\, a. [L. convertibilis: cf. F.
   convertible.]
   1. Capable of being converted; susceptible of change;
      transmutable; transformable.

            Minerals are not convertible into another species,
            though of the same genus.             --Harvey.

   2. Capable of being exchanged or interchanged; reciprocal;
      interchangeable.

            So long as we are in the regions of nature,
            miraculous and improbable, miraculous and
            incredible, may be allowed to remain convertible
            terms.                                --Trench.

Source : WordNet®

convertible
     adj 1: capable of being exchanged for or replaced by something of
            equal value; "convertible securities" [syn: {exchangeable}]
            [ant: {inconvertible}]
     2: designed to be changed from one use or form to another; "a
        convertible sofa"; "a convertible coupe"
     3: capable of being changed in substance as if by alchemy; "is
        lead really transmutable into gold?"; "ideas translatable
        into reality" [syn: {transformable}, {translatable}, {transmutable}]

convertible
     n 1: a car that has top that can be folded or removed
     2: a corporate security (usually bonds or preferred stock) that
        can be exchanged for another form of security (usually
        common stock) [syn: {convertible security}]
     3: a sofa that can be converted into a bed [syn: {sofa bed}]