Here's what rhymes with undecodable.
erodible Words that almost rhyme with undecodable
notable potable quotable approachable unapproachable inapproachable irreproachable reproachable knowable sociable emotional devotional disposable negotiable notional nonnegotiable revokable controllable unknowable unsociable renegotiable consolable promotional inconsolable unemotional uncontrollable overemotional