1. In my humble opinion

Encyclopedia: IMHO

• sororicide
• optical telescope
• optically
• optician
• optics
• optimal
• optimally
• optimisation
• optimise
• optimism
• optimist
• optimistic
• optimistically
• optimization
• optimize
• optimum
• option
• optional
• optionally
• optometrist
• optometry
• opulence
• opulent
• opulently
• Opuntia