The last detail added or change made to something to make it complete. Let's not spend too much longer on this. Let's just put the finishing touch on it and get it ready for production. He's been putting the finishing touches on that painting for so long now, I'm starting to think he'll never be satisfied with it.
Farlex Dictionary of Idioms. © 2015 Farlex, Inc, all rights reserved.
The final stroke(s) that ensure completion or perfection. The term is derived from painting, that is, the last stroke of the artist’s brush, and was soon transferred to any creative effort, ranging from cake-baking to assembling a costume. Its earliest appearance in print dates from the mid-eighteenth century, and Eric Partridge concluded it became a cliché within a hundred years.
See also: finish
The Dictionary of Clichés by Christine Ammer Copyright © 2013 by Christine Ammer