1. With no problems or difficulties
   "put the plans into effect quickly and smoothly"
   - swimmingly 
2. In a smooth and diplomatic manner
   "'And now,' he said smoothly, 'we will continue the conversation'"

See also: smooth

• firewall
• firewater
• fireweed
• firewheel tree
• firewire
• firewood
• firework
• firing
• firing chamber
• firing line
• firing mechanism
• firing off
• firing party
• firing pin
• firing range
• firing squad
• firkin
• firm
• firm omelet
• firm up
• firmament
• firmamental
• firman
• firmer chisel
• Firmiana