Nautical, a line or cord, from 150 to 200 fathoms in length, fastened to the log-chip by means of three legs of cord, and wound on a reel, called the log-recl. See log.(noun)
The Century Dictionary (Public Domain)
Use "log-line" in a sentence
"Just as you said, people want to know the essence of the story before they buy a book or commit to reading it – a great log-line will help you at every step of the way. on 29 Mar 2010 at 6: 20 pm Samantha Clark"
"Quite methodically, just as part of the day's work, the steward chopped down with his knife, catching the log-line between the steel edge and the rail."
"Bill Quigley had managed to catch the lazily moving log-line and were clinging to it."