A loose sentence is one in which the meaning is complete at one or more points before the end.
A loose sentence may be broken at some point before the end, and up to that point be grammatically a complete sentence.
With this line ends the long, loose sentence that began with line 37.
Theoretically the periodic sentence is better than the loose sentence; for it economizes attention.
a complex sentence in which the main clause is followed by subordinate clause(s) or modifier(s)