1. Open to doubt or suspicion
   - doubtful, dubious, dubitable, doubtable

See also: questionable

• olio
• olivaceous
• olive
• olive branch
• olive drab
• olive family
• olive oil
• olive ridley
• olive tree
• olive-brown
• olive-colored
• olive-coloured
• olive-drab uniform
• olive-gray
• olive-green
• olive-grey
• olive-sized
• olive-tree agaric
• olivelike
• olivenite
• Oliver
• Oliver Cromwell
• Oliver Ellsworth
• Oliver Goldsmith
• Oliver Hardy