Here's what rhymes with derivational.
educational vocational relational rotational locational occupational operational informational motivational observational sensational situational vibrational foundational generational gestational translational associational correlational ideational subnational variational mutational avocational invitational aberrational probational organizational gravitational recreational conversational organisational inspirational navigational coeducational improvisational nonvocational denominational representational conformational congregational computational intergenerational transformational confrontational noneducational nonoccupational nonoperational nondenominational interdenominational nonrepresentational Words that almost rhyme with derivational
occasional available saleable salable assailable capable payable attainable insatiable unshakable unshakeable unsaleable bailable unsalable resalable obtainable sustainable unavailable changeable debatable unassailable repayable breakable trainable claimable gradable persuadable conveyable incapable inescapable traceable unattainable unchangeable ascertainable inflatable unbreakable erasable irreclaimable reclaimable mistakable unmistakable interchangeable exchangeable explainable irreplaceable unobtainable unsustainable maintainable replaceable degradable untraceable biodegradable embraceable nonbreakable microwavable nonexchangeable noninterchangeable