What is the superlative of long-term?

Question

I was writing my history essay earlier today on the effects of the First World War and in my conclusion I was comparing the four causes I had discussed in the essay.

I then was half-way through my sentence when I struggled to think of the superlative of long-term.

Both

the longest-term cause was...

and

the most long-term cause was...

struck me as viable options, however neither sounded correct to me at the time. I also thought ofgreatest and most chronic afterwards, although by then it was too late. Greatest also perhaps connotes importance, which is undesirable in the context.

In the end I rephrased my sentence to escape the predicament and although I cannot remember what I wrote instead I believe it was less effective than a sentence with the superlative of long-term.

Answer 1

Perhaps most enduring or most persistent might work.

It depends on whether you are trying to convey most remote in time but significant or having an effect for the longest period. The two examples here reflect the latter.

Answer 2

'long-term' is an indefinite measure. If you need to compare several 'long-term' problems, it is better to just define the actual time units and drop 'long-term' enirely.

I do have a small affection for 'long-termiest' though.

Answer 3

Though it is not a frequent expression, I see nothing wrong with 'the longest-term' causes.

However if I were discussing the complex matter of the origins of the First World War, I think I would speak of the 'longest-term causes' as either the 'profound' or the 'deep-rooted'. e.g. The effects of a century of post-Napoleonic stress, aggravated by the inherent instability of burgeoning nationalism in a Europe of nation states. And this in the context of finite world resources, with no international secretariat such as the UN to resolve disputes'

Then there would be the 'immediate causes', the assassination of the Archduke etc. . The degrees in between, e.g. the German insistence on building a navy, could be a combination of 'less immediate', 'less profound' etc.

Answer 4

Longest long-term would be the superlative form but it sounds clumsy and off; although there are some usages in Google Books.

A better and more natural way to say it is longest-lasting which is the superlative of long-lasting. It is much more common, even in the context of war.

Here is a usage I've found where the superlative adjective longest-lasting modifies effects in the context of World War II:

One of the longest-lasting effects of the interaction of science and technology during World War II was the rapid growth of research laboratories in the United States.

_{World War II in Asia and the Pacific and the War's Aftermath, with General Themes: A Handbook of Literature and Research - edited by Loyd E. Lee, Robin Higham}

Here is another relevant usage in the context of war:

Throughout the same period, war imprisonment, as one of the longest-lasting effects of the war, provided a further social projective surface for collective represenations of war and the military.

_{Postwar Soldiers: Historical Controversies and West German Democratization, 1945–1955 - Jörg Echternkamp}