'smoothly-ended' originates from the combination of 'smoothly,' derived from Old English 'smōð,' meaning 'even or level,' and 'ended,' from Old English 'endian,' meaning 'to bring to a conclusion.'

'smoothly' evolved from the Old English 'smōð,' while 'ended' transformed from the Old English 'endian,' eventually forming the modern English compound 'smoothly-ended.'

Initially, 'smoothly' meant 'even or level,' and 'ended' meant 'to bring to a conclusion.' Together, they evolved to describe a process that concludes without issues.