has/s, z, əz, həz; strong haz/ verb

• operational research
• operations research
• operations room
• operative
• operator
• operculum
• operetta
• operon
• ophicleide
• ophidian
• ophite
• ophthalm-
• ophthalmia
• ophthalmic
• ophthalmic optician
• ophthalmo-
• ophthalmologist
• ophthalmology
• ophthalmoscope
• -opia
• opiate
• opine
• opinion
• opinionated
• opinion poll