truism

noun

1. A self-evident or obvious truth.

   “It is a truism that the site of stations is conditioned by history and geography, but Dover Marine especially owes its fascinating and unusual layout to these two factors.”

   “It is a truism that the people who attend a rally for President Trump more than two years before he’s on the ballot again are generally strong supporters of President Trump.”

   “The phrase If something exists, there is porn of it used to be a clever internet meme; now it’s a truism.”

2. A banality or cliché.

   “After a little decent sorrow had been put forth for the late "severe affliction," joined with some weariful truisms about resignation to the will of Providence, the rest of the epistle was filled up with reproofs about her ladyship's extraordinary and improper conduct in setting off without his consent!”

   “A medical “truism” holds that nose hair filters the air we breathe and therefore protects us from infection by airborne viruses, bacteria and other pathogens. But, as is often the case with truisms, its history may be more venerable than verified.”