Here's what rhymes with conventional.
intentional unconventional attentional dimensional unintentional extensional threedimensional twodimensional multidimensional Words that almost rhyme with conventional
sectional confessional sentinel concessional conceptional convectional sensual seminal obsessional complexional sensible congenital exceptional festival vegetable amenable congressional genital retinal commendable directional sceptical segmental untenable correctional tenable inflectional tentacle unexceptional amendable inflexional recessional spendable pentacle perceptional bendable medical professional chemical terrible acceptable accessible cerebral intestinal marital spectacle parable plentiful skeletal skeptical insensible lamentable unbearable legible bearable testable unprofessional contestable processional wearable weldable comestible connectable unwearable connectible quenchable flexible numerical clerical perceptual susceptible credible homosexual perceptible textual unacceptable contemptible dependable pedestal receptacle defensible illegible impeccable ineffable ostensible unforgettable alchemical bidirectional chimerical compressible execrable expendable presentable preventable unquenchable urogenital inedible collectible correctable undependable breathable collectable extendable perfectible recommendable preventible stretchable unpreventable electable spreadable incredible respectable heterosexual inaccessible detectable inflexible detestable impregnable polemical trigeminal unidirectional delectable digestible incontestable indefensible psychosexual undetectable dispensable extensible nonprofessional prophetical impressible insusceptible repairable suggestible forgettable subprofessional suppressible detectible hypothetical indispensable biochemical comprehensible irrepressible premarital regrettable expressible geochemical incompressible indigestible photochemical paramedical semiprofessional premedical nonclerical nonnumerical noncollectable inexpressible reprehensible extramarital histochemical intertextual intracerebral physicochemical anticlerical paraprofessional alphanumerical gastrointestinal musculoskeletal immunohistochemical