Here's what rhymes with thermionic.
ionic tonic sonic conic phonic bionic chronic ironic chorionic iconic mnemonic symphonic subsonic daemonic avionic embryonic harmonic colonic demonic sardonic ganglionic laconic synchronic monophonic acetonic hegemonic tectonic supersonic diachronic histrionic hypertonic isotonic monotonic platonic polyphonic catatonic diatonic ultrasonic pathognomonic planktonic telephonic hydroponic stereophonic infrasonic electronic philharmonic quadraphonic quadrophonic architectonic microelectronic Words that almost rhyme with thermionic
comic atomic anatomic genomic ergonomic subatomic economic autonomic diatomic taxonomic uneconomic agronomic astronomic tragicomic gastronomic socioeconomic macroeconomic microeconomic logic topic folic gothic semiotic boric iambic meiotic myopic hayrick rollick shambolic symbolic cosmic toxic aortic chaotic erotic garlic neurotic caustic melodic idiotic symbiotic tropic anabolic atopic biotic formic frolic gnostic karmic meteoric bardic cirrhotic seraphic subtopic carsick historic periodic antibiotic aquatic exotic hydraulic caloric geologic hypnotic narcotic psychotic systolic carbolic necrotic phenolic pyloric anarchic anoxic cathodic euphoric fibrotic nephrotic robotic sclerotic thrombotic folkloric homoerotic vitriolic xenophobic ecologic heartsick strophic allegoric sophomoric theosophic chopstick placekick alcoholic metabolic patriotic philosophic physiologic biologic despotic episodic isotropic neurologic pathologic ascorbic etiologic hyperbolic isotopic metaphoric psychologic spasmodic synoptic yardstick agnostic basaltic catabolic cathartic lethargic nontoxic polymorphic antarctic arthroscopic bucolic demagogic diabolic hierarchic acrostic rhapsodic workaholic nonnarcotic subtropic aetiologic chocoholic seismologic shopaholic chocaholic horologic apostolic cytotoxic diastolic histologic philanthropic anisotropic endoscopic metamorphic morphologic parabolic pharmacologic hematologic melancholic oligarchic orthodontic pedagogic psychotropic quixotic fluoroscopic unpatriotic misanthropic subarctic haematologic noncaloric gynaecologic astronautic diagnostic microscopic hydrochloric prehistoric catastrophic macroscopic prognostic atherosclerotic immunologic gynecologic stereoscopic telescopic microcosmic gyroscopic nonalcoholic macrobiotic posthypnotic meteorologic anthropomorphic epidemiologic spectroscopic peristaltic bacteriologic antispasmodic stroboscopic kaleidoscopic submicroscopic electroscopic