1. In a believable manner
   "he acted believably sincere" 
2. Easy to believe on the basis of available evidence
   - credibly, plausibly, probably, tenably

See also: believable

Antonym: unbelievably

• approve
• approved
• approver
• approving
• approvingly
• approx
• approximate
• approximate range
• approximately
• approximation
• approximative
• appurtenance
• appurtenant
• APR
• apractic
• apraxia
• apraxic
• Apresoline
• apricot
• apricot bar
• apricot sauce
• apricot tree
• April
• April 14
• April fool