O — oa ob oc od oe of og oh oi ok ol om on oo op or os ot ou ov ow ox oy oz
oodles |ˈuːdlz| — a large number or amount
oof |uːf| — A sound mimicking the loss of air, as if someone's solar plexus had just been struck.
oolite |ˈəʊəlaɪt| — (geology) A rock consisting of spherical grains within a mineral cortex accreted around a nucleus, often of quartz grains.
oolitic |ˌəʊəˈlɪtɪk| — (geology) Made up of, or containing oolites
oology |əʊˈɑːlədʒiː| — the branch of zoology that studies eggs (especially birds' eggs and their size, shape, coloration, and number)
oolong |ˈuːlɒŋ| — Chinese tea leaves that have been partially fermented before being dried
oomph |ʊmf| — attractiveness to the opposite sex
oosperm — (biology) The ovum, after fusion with the spermatozoon in impregnation.
ooze |uːz| — any thick, viscous matter
oozing |ˈuːzɪŋ| — the process of seeping
oozy |ˈuːzɪ| — leaking out slowly