Opo

[dolphin] Opo was a bottlenose dolphin who became famous throughout New Zealand during the summer of 1955-56 for playing with the children of the small town of Opononi on the Hokianga harbour. Opo was a wild dolphin who started following fishing boats around Opononi in early 1955 after her mother had been killed, and would swim daily in the...
Found on http://en.wikipedia.org/wiki/Opo_(dolphin)

OPO

One person operation
Found on http://www.encyclo.co.uk/local/20749

OPO

One Person Operation; the standard train operating regime used on London Underground. Conversion from two-person crews began in 1984 and was finally completed in 2000.
Found on http://www.trainweb.org/tubeprune/dictionary.htm

OPO

Organ Procurement Organization
Found on http://www.encyclo.co.uk/local/20895
No exact match found