1. With unflagging resolve
   - endlessly, ceaselessly, incessantly, unendingly, continuously, unremittingly

See also: unceasing

• butterfly bush
• butterfly collector
• butterfly effect
• butterfly flower
• butterfly nut
• butterfly orchid
• butterfly orchis
• butterfly pea
• butterfly plant
• butterfly ray
• butterfly stroke
• butterfly valve
• butterfly weed
• butterfly-shaped
• butterflyfish
• butterhead lettuce
• buttermilk
• buttermilk biscuit
• buttermilk pancake
• butternut
• butternut squash
• butternut tree
• butterscotch
• butterweed
• butterwort