(a.) Capable of being transmuted or changed into a different substance, or into something of a different form a nature; transformable.

all one all the same changeable coequal commutable commutative coordinate correspondent corresponding equal equalizing equiparant equipollent equivalent even exchanged give-and-take identical interchangeable interchanged liquid modifiable much the same mutual negotiable permutable reciprocal reciprocating reciprocative resolvable retaliatory returnable standard swapped switched tantamount traded transformable transitional transmutable transposed