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

• Stephen Hawking
• Stephen Jay Gould
• Stephen Leacock
• Stephen Michael Reich
• Stephen Samuel Wise
• Stephen Sondheim
• Stephen Spender
• Stephen Vincent Benet
• Stephen William Hawking
• Stephenson
• stepladder
• stepmother
• stepney
• stepparent
• steppe
• stepped line
• stepper
• stepping down
• stepping motor
• stepping stone
• steprelationship
• steps
• stepsister
• stepson
• stepwise