1. In contact with, on top of
   "the book upon the table"
   - on

1. Being up to particular standard or level especially in being up to date in knowledge
   "up on the news"
   - abreast, au courant, au fait, apace [N. Amer]

See also: informed

Encyclopedia: Upon

• genus Orthopristis
• genus Orthotomus
• genus Orycteropus
• genus Oryctolagus
• genus Oryx
• genus Oryza
• genus Oryzomys
• genus Oryzopsis
• genus Osmanthus
• genus Osmerus
• genus Osmunda
• genus Ostrea
• genus Ostrya
• genus Ostryopsis
• genus Otaria
• genus Othonna
• genus Otis
• genus Otus
• genus Ouranopithecus
• genus Ovalipes
• genus Ovibos
• genus Ovis
• genus Oxalis
• genus Oxandra
• genus Oxybelis