Optimist rhymes with:
agronomist, alchemist, economist, islamist, agronomist, alchemist, chemist, combest, conformist, economist, extremist, islamist, nonconformist, palmist, reformist
agronomist, alchemist, economist, islamist, agronomist, alchemist, chemist, combest, conformist, economist, extremist, islamist, nonconformist, palmist, reformist