Residual rhymes with:
gradual, annual, asexual, audiovisual, biannual, bisexual, conceptual, consensual, continual, contractual, emanuel, emmanuel, eventual, factual, gradual, habitual, ineffectual, intellectual, manual, massmutual, menstrual, parimutuel, pascual, perpetual, punctual, ritual, sexual, transsexual, virtual
Residual sounds like:
ragsdale, recital, rectal, reichstuhl, reschedule, resdel, resettle, restyle, rhizoidal, riccitelli, rightly, rigidly, rookstool, ruggedly, rustle