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

See also: constant, energetic

• wordmonger
• wordnet
• wordplay
• words
• words per minute
• wordsmith
• Wordsworth
• Wordsworthian
• wordy
• work
• work animal
• work at
• work camp
• work ethic
• work experience
• work in progress
• work of art
• work off
• work on
• integrated
• integrated circuit
• integrated data processing
• integrated logistic support
• integrating
• integration