prolongation vs length

prolongation and length both are nouns.

Word	Noun	Adjective	Verb	Adverb
prolongation	Yes	No	No	No
length	Yes	No	No	No

As nouns, length is a hypernym of prolongation; that is, length is a word with a broader meaning than prolongation:

Other hypernyms of prolongation include duration.

prolongation (noun)	length (noun)
the act of prolonging something	a section of something that is long and narrow
amount or degree or range to which something extends	the linear extent in space from one end to the other; the longest dimension of something that is fixed in place
the consequence of being lengthened in duration	continuance in time
	the property of being the extent of something from beginning to end
	size of the gap between two places