A secular trend is a long term trend, that from its name, ought to mean that a particular sector of the economy is changing. For example, the disappearance of the horse-and-buggy with the advent of the automobile was a secular change. Cyclical trends refer to the business cycle, where a business opportunity generates new companies or products that reap good profits, those profits bring in copy-cat competitors that kill off the profits, a bunch of the companies then go under, consequently reducing supply, and then the cycle repeats. The DRAM market is cyclical.
Secular and cyclical make perfect sense in fundamental analysis of companies, and they are important tools for being on the right side of a trend. In fact, they are just another way of saying "the trend," and they differ in long or short term. But that's not how they are used in the popular press these days. Most of the references one sees these days use them in a technical sense, meaning an analysis of the stock market direction, not of companies. That is mostly hogwash.
The best I can determine is that the adherents believe that the stock market goes in 18 year secular cycles, we just had a big upward push from the 1980's, so we're overdue for a contraction. So any upward stock market push is just cyclical in the overall secular down trend.
Here are just a few things that are different: Globalization; an effective Federal Reserve from the 1980's onward for the first time in the history of the world; no Gold Standard. Just looking at a chart of the DOW and saying '18 years up, then 18 years down or flat' based on past performance is, well, sort of stupid.
Here's the opposite of what everyone else is saying:
● The energy market is in a cyclical upswing, not a secular change to higher energy consumption. Energy consumption per-capita is dropping, population growth is slowing, GDP dependence on energy has dropped. We have some current short term supply disruptions, that are going to be over-compensated for with new technological and supply competition, sooner rather than later. That is the definition of cyclical, not secular. There is no long term energy shortage.
● The technology market is in a secular upswing, with cyclical ups and downs. Can you honestly think of a single market space that is not somehow effected by microchips? RFID and bar-code scanning of canned fruit. Computerized calculation of maximum board feet from timber prior to cutting, etc. And of course all the obvious changes - fewer secretaries and more computers, etc. That is the definition of a secular change, and it shows no sign of abating.