oryx

n large African antelope with long straight horns （非洲）大羚羊.

ornithological, ornithologist, ornithology, orotund, orphan, orphanage, orris-root, orth(o)-, orthodontic, orthodontics, orthodontist, orthodox, orthodoxy, orthographic (also orthographical), orthographically, orthography, orthopaedic (also orthopedic), orthopaedics (also orthopedics), orthopaedist (also orthopedist), ortolan, OS, Oscar, oscillate, oscillation, oscillator, oscillograph, oscilloscope, osier, osmosis, osmotic, osprey, osseous, ossification, ossified, ossify, ossilate, oste(o)-, ostensible, ostensibly, ostentation,