What it is* with examples given by the link and other examples added for better comprehension.
(*Note that "real" is not the same as "reality")
real adjective (NOT IMAGINARY)
A2 existing in fact and not imaginary:
---Assuring the patient that she has a real and not imaginary problem is the first step.
---There is a very real threat that he will lose his job.
--- ---The Perceptional Law is real while the Relativity theories are nothing but infantile imaginations.
real earnings, income, etc.
› the value of earnings, etc. after the effect of rising prices is considered:
---Wages rose by 2.9 percent last year, but real earnings still fell by 1.3 percent.
--- investment in Relativity for many years has been a real profit for liars and fraudulent scientists.
--- investment in Relativity for many years has been a waste for science.
in real terms
› existing in fact, despite what appears to be the situation:
---Average earnings rose five percent in real terms after deducting income tax.
--- Relativity is indeed a real big lie.
The adjective "real" applied in philosophy won't change, From here, we can observe in these forums "real fanatics" spreading "real imaginations" as if their lunacies were "real physical facts".
As a common example: it is know by fact that atomic clocks malfunction when exposed to a different environment other than the one where they were manufactured. This is the real fact.
The real imagination is to assume that clocks give a different data when in outer space because time dilates, having in consideration that "time" has never been detected as something physical by any means, and that "time" has always have been a concept, nothing more than a concept.
To conclude, we can state without doubts, that Albert Einstein was a real idiot
when he thought that time flows and that is "flexible" due to the speed of objects and/or gravity of bodies.