Lexical Definition

‎ἑταῖρος‎ hetaîros (het-ah'-ee-ros) friend ^G:N-M
from (a clansman)

fellow, friend.

• a comrade

Abbott-Smith

ἑταῖρος, -ου, ὁ [in LXX chiefly for רֵעַ and cognate forms, also Si 11:6 37:2ff., al. ;]
a companion, comrade: Mt 11:16 (WH, ἑτέροις); voc., as term of address, my friend: Mt 20:13 22:12 26:50.†

Abbott-Smith References

Liddell-Scott-Jones

ἑταῖρος-ος,

Epic dialect and Doric dialect also ἕγᾰρος, [Refs 6th c.BC+], ὁ:— comrade, companion, in [Refs 8th c.BC+] especially of the followers of a chief, comrades-in-arms, [Refs 8th c.BC+]; messmate, [Refs]; fellowslave, [Refs 8th c.BC+]; later, as a term of address, φίλ᾽ ἑταῖροςε [Refs 6th c.BC+]; ὦταῖρε Scol. cited in [ἑταῖροςε">NT+5th c.BC+] partner of my feast, [Refs]; πόσιος καὶ βρώσιος ἑταῖροςοι messmates, [Refs 6th c.BC+]

__2 metaphorically, of things, ἐσθλὸς ἑταῖροςος, of a fair wind, [Refs 8th c.BC+]
__3 pupil, disciple, e.g. of Socrates, [Refs 5th c.BC+]: plural, fellow-pupils, [Refs 2nd c.AD+]
__4 of political partisans [Refs 5th c.BC+]; οἱ περὶ αὐτὸν ἑ. his club-mates, [Refs 4th c.BC+]
__5 members of a religious guild, [Refs]
__6 rarely of lovers, [Refs 7th c.BC+]
__7 ἑταῖροςοι, οἱ, the guards, i.e. the cavalry of the Macedonian kings, [Refs 4th c.BC+] see at {πεζέταιρος}, [Refs 2nd c.AD+]; to be distinguished from the king's immediate retinue (compare above [Refs 2nd c.AD+]; of the [Refs 1st c.AD+]
__8 as adjective, associate of, τὸ ἐπιθυμητικὸν ἡδονῶν ἑ. [Refs 5th c.BC+] your closest companions, [Refs 1st c.AD+]; σαργῶν γένος πέτρῃσιν ἑ. constant to the rocks, [Refs 2nd c.AD+]: absolutely, of animals, gregarious, [Refs]
__II ἑταίρα, Ionic dialect ἑταίρη, Epic dialect ἑτάρη [ᾰ], ἡ, companion, Ἔρις..Ἄρεος..κασιγνήτη ἑτάρη τε [Refs 8th c.BC+]; Ποσειδάωνος ἑ., of a submerged city, [Refs 3rd c.BC+]
__II.2 courtesan, [Refs 5th c.BC+]; opposed to πόρνη (a common prostitute), [Refs 4th c.BC+]; opposed to γαμετή, [Refs 6th c.BC+]

_{LSJ Scripture Refs: Matt.20.13}