O
- Orange Free State, [26], [38], [52], [133], [134] et seq., [143], [144], [145], [148], [162], [311-318], [469], [471], [472]
- Orange River Sovereignty, [129], [131], [132], [144]
- Orange River, [9], [34] et seq., [119], [123], [140], [145]
- Ostriches, [21], [27], [135], [436]
- Oudzi River and Waterfall, [250], [251]
- Ox-Waggon, [182-186], [203-208], [226], [231]