oracle C2+

/ˈɔrəkəl/ a person or agency considered to give wise or authoritative guidance

orotund C2+

/ˈɔrətʌnd/ (of the voice) full and resonant; (of speech) pompous or bombastic

orate C2+

/ˈɔreɪt/ to speak formally and at length, often pompously

osculate C2+

/ˈɑskjəleɪt/ to kiss; in geometry, to touch so as to share a common tangent

osculation C2+

/ˌɑskjəˈleɪʃən/ the act of kissing; in geometry, contact of a high order between curves