O (disambiguation) Ö Ơ Õ Ø Ó P&O O O-methylated flavonoid O' O visa Ò O-GlcNAc O Antiphons O A e o Z Douglas O-38 O class Open O Pui O O series O line Big O O lucenti, o sereni occhi Oʻ O. Henry Award Tai O Big O notation Ping-O-Tronic O Come, O Come, Emmanuel Haplogroup O-M119 O-ring O Tannenbaum Ɵ Yeshe-Ö Ó Paí, Ó O Tempo e o Vento P&O Cruises O-type star O (Cyrillic)