1. Without problems or difficulties
   "NASA reported a trouble-free launch"

See also: untroubled

• backache
• backband
• backbeat
• backbench
• backbencher
• backbend
• backbite
• backbiter
• backblast
• backblocks
• backboard
• backbone
• backbreaking
• backchat
• backcloth
• backcomb
• backcross
• backdate
• backdoor
• backdown
• backdraft
• backdraught
• backdrop
• backed
• backer