What is the meaning of Solvable?
Capable of being solved.
Having terminating derived series; see 
Solvable group on Wikipedia.Wikipedia
Having a Galois group which is solvable.
Having terminating derived series (this is a distinct notion from the derived series of a group); see Solvable Lie algebra on Wikipedia.Wikipedia
Such that the set of inputs for which the answer is yes is recursively enumerable.
Capable of being dissolved or liquefied.
Able to pay one's debts.
Capable of being paid and discharged.
Source: wiktionary.orgSearch words containing