Lexical Definition

‎ἅγιος‎ hágios (hag'-ee-os) holy ^G:A
from (an awful thing) (compare ‎ἁγνός‎, ‎θάλπω‎)

(most) holy (one, thing), saint.

• sacred (physically, pure, morally blameless or religious, ceremonially, consecrated)

Abbott-Smith

ἅγιος, -α, ον (< τό ἅγός, religious awe; ἅζω, to venerate), [in LXX chiefly for קֹ֫דֶשׁ;]
primarily, dedicated to the gods, sacred (Hdt.; rare in Att., never in Hom., Hes. and Trag., who use ἁγνός), hence, holy, characteristic of God, separated to God, worthy of veneration.
1. Its highest application is to God himself, in his purity, majesty, and glory: Lk 1:49, Jo 17:11, Re 4:8. Hence
(a) of things and places which have a claim to reverence as sacred to God, e.g. the Temple: Mt 24:15, He 9:1;
(b) of persons employed by him, as angels: I Th 3:13; prophets, Lk 1:70; apostles, Eph 3:5.
2. Applied to persons as separated to God's service:
(a) of Christ, Mk 1:24, Jo 6:69, Ac 4:30;
(b) of Christians, Ac 9:13, Ro 1:7, He 6:10, Re 5:8.
3. In the moral sense of sharing God's purity: Mk 6:20, Jo 17:11, Ac 3:14, Re 3:7.
4. Of pure, clean sacrifices and offerings: I Co 7:14, Eph 1:4.
SYN.: ἁγνός, pure, both in ceremonial and spiritual sense; ἱερός (sacer), sacred, that which is inviolable because of its (external) relation to God; ὅσιος (sanctus as opp. to nefas), that which is based on everlasting ordinances of right. (Cf. Tr., Syn., §lxxxviii; DB, ii, 399 f.; Cremer, 34, 594-601; MM, VGT, s.v.)

Abbott-Smith References

Liddell-Scott-Jones

ἅγιος [ᾰ], α, ον,

devoted to the gods:

__I in good sense, sacred, holy:
__I.1 of things, especially temples, ἈΦροδίτης ἱρὸν ἅ.[Refs 5th c.BC+]; ἱρο᾽ν Ἡρακλέος ἅ.[Refs 5th c.BC+]; μητρός.. ἐστι πατρὶς ἁγιώτερον[Refs 4th c.BC+]; ἅ., τό, temple, [LXX+NT]Holy of Holies, [NT]
__I.2 of persons, holy, pure, [LXX+5th c.BC+] οἱ ἅ. the Saints, [NT] πνεῦμα ἅ. the Holy Spirit, [NT] adverb ἁγίως καὶ σεμνῶς ἔχειν[Refs 5th c.BC+]
__II in bad sense, accursed, execrable, [Refs 8th c.BC+]; rare in Attic dialect (see. above). (Possibly cognate with Sanskrit yajati 'sacrifice'.)

_{LSJ Scripture Refs: LXX.Exod.26.33 ☩ Heb.9.2 ☩ Heb.9.3 ☩ LXX.Deut.7.6 ☩ 1Cor.6.1 ☩ Matt.3.11}