1. Lacking self-confidence
   "a very unsure young man"
   - diffident, shy, timid 
2. Lacking or indicating lack of confidence or assurance
   "unsure of himself and his future"; "moving with unsure steps"
   - uncertain, incertain

See also: ambivalent, assurance, authority, certainty, confidence, doubtful, dubious, groping, self-assurance, self-confidence, sureness

Antonym: sure

• oesophagoscope
• oesophagus
• Oesterreich
• oestradiol
• Oestridae
• oestriol
• oestrogen
• oestrone
• oestrus
• Oestrus ovis
• oeuvre
• of
• of a sort
• of a sudden
• of age
• of all time
• of course
• of each person
• of import
• of late
• of necessity
• of sorts
• of sound mind
• of the essence
• of unsound mind