What is ariya or noble?
This term is used in multiple places like Four Noble Truths (cattāri ariyasaccāni), Noble Eightfold Path (ariya aṭṭhaṅgika magga), noble sangha (ariya saṅgha).
although wondering why one who steady teaches others about what is Sublime, Higher, Perfect, ask about the meaning of Ariya...
Ariya, (adj. -n.) (Vedic ārya, of uncertain etym. The other Pāli forms are ayira & ayya) 1. (racial) Aryan D. II, 87. ‹-› 2. (social) noble, distinguished, of high birth.—3. (ethical) in accord with the customs and ideals of the Aryan clans, held in esteem by Aryans, generally approved. Hence: right, good, ideal.
In regard of people:
The answer by Dhammadhatu isn't that bad aside of a grammar issue making "without enemy" to a dual or in both direction valid, but actually means that oneself sees nothing and nobody as enemy. It might be, and even in the Buddhas case, that an Ariya has people around who look after harming or winning over him.
Ariya is a Sublime person beyond ordinary, worthy of hospitality, veneration and gifts, one who has metta toward all beings, one having reached tge level of integrity, the Stream, has faced the Deathless and to certain amount awakened. One training after reaching this ancestor-ship is called a lower-Ariya (Dhamma-, Faith-follower practicing proper, having universal metta; having heard the good Dhamma and regards the Gems, bound to become Ariya before death).
In regard of qualities and deeds: Likewise Sublime, Exalted, not ordinary, common.
So if one touches or 'inter'-acts with the Sublime Gems one is wise to always regard them as Sublime, beyond even kings, world-ruler, Gods, father, mother, child, oneself.
Disregard or even harm of what is Ariya has very disadvantageous impact not only downwardly but can even totally cut one of from an upward path for long time.
This is why asking for forgiveness is a common and frequently conducted practice as one would be otherwise out of refuge, cut off the Gems.
Worthy to mention as very importand: One who does not recognize such as Ariya, Sublime, a common 'communist' is absolutly incapable to either work his way upwardly nor ever able to reach path or fruits, like one denying swimming is possible is actually bound to drow.
[Note that this isn't given for stacks, exchange, other world-binding and common trades but to gain escape in becoming an Ariya, not staying a slave of commu/onism]
The events of the Pali Canon took place during the historical period when the more civilized culture of Aryans (likely descendants of the great Mesopotamian civilization, perhaps of Assyrian, Babylonian, Persian, Iranian origins) were migrating into the valley of Indus and mixing with the local Dravidian cultures which were many centuries behind in social order, economic relationships, and technology.
By the Buddha's time this millennium-long process was maybe 3/4 complete. So by that time the word Arya stopped referring to the ethnicity and instead came to mean "civilized" or "advanced" or "savvy", hence the use we know.
From this we can see why connotations of the word "Aryan" are similar to those of the other word Buddha used a lot, "samma" (usually translated as "right"). Samma means "high quality" or "made to high standards", and Aryans are the bearers of those high standards, people of care and discernment in ethical behavior as well as in analytical thinking.
Therefore, Four Aryan Truths, Aryan Eightfold Training, Aryan Community -- are the Truths, the Training, and the Community of the high-standards people, the people of enlightenment.
The view, thought, speech, action, livelihood, effort, mindfulness & concentration that is towards Nibbana (and only Nibbana), that will be Noble. The knowledge and the liberation of such practice, that will be Noble.
So in short, Nibbana or the practice towards it (i.e. the Noble Eight Fold Path), that is what is Noble.
Four Noble Truths - one who has realized the Four Noble Truths has attained Nibbana.
Noble Eight Fold Path - the practice one undertakes to attain Nibbana.
Noble Sangha - the four pairs, the eight kinds of persons developing or developed the Noble Eight Fold Path and have attained the fruits of it.
If you carefully read The Great Forty discourse you can see this. That is a great discourse to understand the Noble Eight-Fold Path.
“And what is the right view that is noble, without effluents, transcendent, a factor of the path? The discernment, the faculty of discernment, the strength of discernment, analysis of qualities as a factor for awakening, the path factor of right view in one developing the noble path whose mind is noble, whose mind is without effluents, who is fully possessed of the noble path. This is the right view that is noble, without effluents, transcendent, a factor of the path.
For anyone looking to learn and develop the Noble Eight Fold Path that will result in the Noble Fruits and attain Nibbana, you can look at the Meditations explained here. (Start with "Noble Eightfold path meditation").
The word “noble” could mean something like excellent, exalted, honourable or respectable, however the word “Ariya” has the meaning “to be without enemies”. So do these two words correspond sufficiently? When we speak of the Ariya Sacca we should understand “Ariya” in the sense of “being without enemies”. Here enemies is meant in the broadest sense, being free of things which aren’t right for us, things which are undesirable, so we’ll be looking at the Noble Truths in this way.
In Buddhist tradition, Ariya refers to the eight types of Ariya people. (Sotapanna,Sakdagami, Anagami,Arahant) in Magga and Phala states (ie4x2=8)