Real is about as Latin of a word as one can find.
It comes from the Latin realis.
Re is a variation on the Latin word res
alis just means: of, related to, connected with, belonging to
So realis is literally that which is related to things.
Res was a Roman staple, e.g. res publica literally public matter or public things.
In the dictionary they also try a trace Res back to Sanskrit:
"From Proto-Italic *reis, from Proto-Indo-European *reh₁ís (“wealth, goods”). Cognate to Old Persian [script needed] (rāy-, “paradise, wealth”), Avestan (rāy-, “paradise, wealth”) and Sanskrit रयि (rayí, “property, goods”)."
And note that in Latin the spelling RES is the same for singular and plural. So its like res are your things. Your land, your house, your bike, your car, your husband or wife, your body, your children, your money, your clothes, your food supply, and any relation in regards to your things. Your stuff! A very simple down to earth word and much less technical than the other Latin word: Existentia
There are hundreds of English words that use RES, e.g. resurrection, residue, reservoir, residence, etc.
The way the Romans used the word is similar to how people use the English word 'thing' or 'matter' or 'stuff'. In English 'thing' or 'matter' is basically used as a placeholder for any word in an ordinary conversation. But in physics and philosophy these words are used differently and people will be trying to figure this stuff out until the Sun explodes.
If we are to use the word REAL in physics and philosophy then we have to define it.
The Latin is literally that which belongs to things. Thing is just synonymous with object, entity, body, etc. What belongs to all things I ask? Form. Form is the primary quality of all things. So real has a lot to do with form. Form refers to that which is bounded or contained from the immediate surrounding. Then if you want you can add the idea of location. So this form has a location. That star you see every morning has form and location. And guess what? Your act of observing it or thinking about it doesn't determine this. The Sun is just there. It stimulates the atoms in your body and forces you to wake up. Very profound!!! So in real there is this sense that the thing is independent to your thought or act of perception.
Your wife you wake up to every morning has form and location. Once you tie the knot you can't escape her. Your car or bike or skateboard has form and location, that magnet you used in science class has form and location, as do all the atoms that constitute these. HOWEVER that woman you dreamed about last night seemed to have a form but no location. If you look around you will not find her. You can think about her, but you can't relate TO HER. Your brain just generated a picture and made a movie of her. Or that triangle you traced in geometry has a form but no location. Or those spacetime lines your curved don't seem to be found. These forms are not real. They have no relation to all the atoms of the Universe.
So its very simple. The Romans were no fools. They conceived and used words like REALIS and EXISTENTIA because some of their Greek neighbors were insane. These are static concepts used to describe objects.
In philosophy and mathematics they start messing around with the word real and for thousands of years this word is never resolved or defined. And then we have mentally ill philosophers, mathematicians and so called physicists preaching to the masses about the word real. And then they build trillion dollar devices to decide what is real or what is not real because they are confused about how the philosophers use the word real.
All these imaginary problems could be resolved in an instant if the philosopher, physicist or mathematician defined the term REAL and used it consistently in his presentations. Simple as that.
so in summary for physics and philosophy I would define
Real: that which has form (object) and location independent of any human action whether thinking, perceiving, observing, measuring, dreaming, hallucinating, etc. Not all objects qualify as real.
Location & Real vs. Existence
Location refers to a static concept (a picture imaged by the brain). Where form is a primary quality of objects used to resolve the ontology of the word referent, location refers to a sort of secondary quality sometimes used to resolve whether or not an object is real and/or exists.
Real and existence are often used to mean the same, however they are strictly speaking a little different. Real is more down to Earth. A sober concept and has to do more with that which has form independent of any sort of human intervention. Existence is more technical. Existence literally refers to that which STANDS OUT and seems to imply the three classic dimension (length, width, and height). So one could argue that existence implies a human observer. But on the other hand if one has a perfect understanding of the crucial word 'Form' and takes into account mercurial assumptions, I think one can do away with need to toy around so much.
But location can be defined more or less in an observer independent manner so as to resolve whether or not an object is real and/or exists
Location refers to the set of static distances from an object to all other objects.
If an object is described by real or exist, one should hypothetically be able to measure its distance to all objects of the Universe. So if superman is real and/or exists he should be located X distance from the Sun, Y from the Moon, Z from the Earth, A from you and so on. One doesn't have to do the measuring but the basic concept is powerful. It serves as a sound conceptual exercise.
Location can tell you right away whether or not some form is imagined or traced. For example a triangle. A triangle is an object. It has form, HOWEVER. does it have location? And even more 'what' could we possibly imagine bounded or contained of a triangle? In between the boundaries all one does is conceptualize space or some other imaginary forms. Space lacks form. So obviously a triangle is an abstract or imaginary form used in some context of utility. A triangle has nothing to do with reality and/or existence and all to do with a human brain conceptualizing. Similar with all concepts such as love, justice, gravity, etc. These concepts have no form, and neither to they have location. Where are you literally going to find love? Love is what an object does.
Really once one takes on some mercurial assumptions all one needs is Form. But now one can make a list of objects and ask whether or not they have location so as to help resolve whether or not they are real or exist. And so it becomes clear that humans imagine objects, hallucinate objects, project objects unto their environment, trace objects on paper and via computers, dream objects, abstracts objects, idealize objects, hypothesize objects, etc. However none of these can be located and strictly speaking they have no form. Their form also has to be described with the same modifiers. They have imaginary form and so on. We thought of them, we pictured them via our brain and used them to think, but there is no what contained, or bounded from immediate surrounding, no essence, no three classic dimensions, etc. You will never be able to locate a triangle or the ideal woman or superman. None of these objects stand out, none have three dimensions, none of them are connected to all the atoms of the Universe much less constituted by atoms. None of them are qualified in the abstract nest called matter. These imaginary objects have no foundation.
Are Memories Real?
Memory is a brain capacity. The brain or neural objects move to re-image an object of the past or imagine objects collectively mediating an event which happened in the past. The objects used in memory are not real since they lack location or a 'foundation' object from which they derive their form. They are imaginary objects or objects of memory. Just like dream objects or objects in hallucination. In this scenario we could just assume the brain and neural objects or human performing an act of memory are real.
Memory refers to a concept about what an object (brain) is able to do. Memory or memories lack form. There aren't any objects called memories constituting one's brain. Strictly speaking, real describes object. Memory lacks form and so relates back to a concept that we worked out about what our brain is able to do. Thus memory is not object and cannot be described by a static comparison called real. Similar with event. Event lacks form.
REAL is a word that describes and helps to discern objects in our act of understanding and communication.
Naming Our Brain-work
We have the ability to name objects (that which has form) or relation between objects that our brain has worked out.
So in assumption each and every name first and foremost refers to concept. Once we think beyond (or transcend) this assumption then we realize that these nominal conceptions either reference an object (whether real, imaginary, hypothetical, and so on and so forth) or they reference some sort of relation or comparison between objects that our brain has worked out (for example love, gravity, number,) and we decided to label by the act of naming or even tracing. The act of naming always relates the human who named to the object named or the conception conceived and so this is a sort of primal concept. And the criteria for figuring out whether or not a human named an object or a concept is form. This Gottlob Frege never figured out. He had his own complex categories, but his investigations are still useful to borrow from.
But the sort of furtive act in all this is naming our conceptions. We work out a relation or comparison between objects and name this relation. So naming sort of works an affinity between us and our brainwork. We reify our brainwork (that is convert concept into object) and establish a sort of false relation in this. We cannot literally relate to a work our brain consummated so we do a trick by reifying. This is sort of a transcendental if you want. And this is what is confusing I think. Its easy to imagine Adam waking up, discerning that which has form and naming it. But then Adam went to retire for the day and started working out relations between all these objects he named and then he named these relations. The way we can resolve whether or not a word concept relates back to object or concept is form. Does the word referent have form? Yes or no?