Automatic rhymes with:
semiautomatic, asymptomatic, semiautomatic, symptomatic, systematic, aromatic, asymptomatic, axiomatic, cinematic, diagrammatic, diplomatic, dramatic, emblematic, epigrammatic, idiomatic, mathematic, melodramatic, problematic, programmatic, psychosomatic, semiautomatic, symptomatic, systematic, telematic, undiplomatic
Automatic sounds like:
adenoids, admits, attendees, attends, attenuates, authentic, automates, automatics, automatix