What is ariya or noble? 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).
Good householder,
although wondering why one who steady teaches others about what is Sublime, Higher, Perfect, ask about the meaning of Ariya...
PTS-dictionary:

Ariya, (adj. -n.) (Vedic ārya, of uncertain etym. The other Pāli forms are ayira &amp; 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 &quot;without enemy&quot; 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]