1. Showing sustained enthusiastic action with unflagging vitality
   "unflagging pursuit of excellence"
   - indefatigable, tireless, unwearying 
2. Unceasing
   "unflagging courtesy"
   - unfailing

See also: constant, energetic

• digitalize
• digitally
• Digitaria
• Digitaria ischaemum
• Digitaria sanguinalis
• digitate
• digitately
• digitigrade
• digitigrade mammal
• digitisation
• digitise
• digitiser
• digitization
• digitize
• digitizer
• digitoxin
• dignified
• dignify
• dignifying
• dignitary
• dignity
• digoxin
• digram
• digraph
• digress