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

• Thursday
• thus
• thus far
• thusly
• thwack
• thwart
• thwarted
• thwarter
• thwarting
• thwartwise
• thy
• thylacine
• Thylacinus
• Thylacinus cynocephalus
• Thylogale
• thyme
• thyme camphor
• thyme-leaved sandwort
• thyme-leaved speedwell
• Thymelaeaceae
• Thymelaeales
• thymic
• thymic acid
• thymidine
• thymine