eco-friendly/eekohʹfrendli/ adj

• on/under oath
• on/under pain of
• onus
• on view
• onward
• onwards
• on welfare
• onychophoran
• -onym
• on your marks
• on your own head be it
• onyx
• oo-
• oocyte
• oodles
• oogamete
• oogamous
• oogenesis
• ooh
• oolite
• oolith
• oology
• oolong
• oompah
• oomph