phylum /fīˈləm/

1. A main grouping of the animal kingdom, corresponding to a division in the plant kingdom
2. A group of languages thought to be related

• optologists
• optology
• optometer
• optometers
• optometric
• optometrical
• optometries
• optometrist
• optometrists
• optometry
• optophone
• optophones
• opt out
• opt-out
• opt-outs
• optronics
• opts
• opulence
• opulences
• opulent
• opulently
• opulus
• opuluses
• opuntia
• opuntias