At its root this word describes whatever squares with reality rather than deceiving. A statement is true when it matches the facts, a person is true when they habitually tell the truth, and a thing is true when it is the genuine article and not a counterfeit. All three are the same idea seen from different angles: the opposite of the word is always a falsehood or a lie.
The New Testament leans on it most heavily in the language of witness and testimony, above all in John's Gospel, where Jesus and his opponents argue over whose word can be trusted. There the question is not merely whether a claim happens to be accurate but whether the witness behind it is reliable, so a true report and a truthful witness stand side by side.
One caution runs through every use: English "true" is broader than this word. A person called true here is honest and not lying, not "loyal" or "faithful" in the way we might speak of a true friend. Keeping the plain sense of not-false in view keeps the reader close to what the writers meant.
Nuances
1aof a statement, testimony, or report: factually true, accurate, matching the facts
when it describes a person, this word means honest and not lying, a nuance English "true" does not naturally carry for peopleJhn 7:18Rom 3:4
Both
for a statement or a testimony, both words mean it matches the facts and is not falseJhn 5:31Tit 1:13
Only true
English "true" often means loyal, faithful, or constant (a true friend), a sense this Greek word does not carry
“truthful”
Comparison data is not available for this English gloss yet.
“genuine”
Comparison data is not available for this English gloss yet.
How alēthēs differs from similar Greek words
ἀληθινόςmeans real or genuine as opposed to a counterfeit or a copy, where this word means truthful or accurate as opposed to false; the real (ἀληθινός) light is the authentic thing, while a true (ἀληθής) witness is one who does not lie
Means truthful, the opposite of lying: it describes a speaker (or God) who tells the truth and does not deceive.Rom 3:4Jhn 7:182Co 6:8
Confirms that a statement or report matches the facts, that what was said actually holds and can be trusted as accurate.Jhn 10:41Jhn 4:18Tit 1:13
Both
Both are rendered true in English and can be attached to the same subject, such as a testimony, so a single verse may use both of one act of witness.Jhn 19:35
Both affirm that something conforms to reality, and in John's writing they shade into one another where truthfulness and genuineness overlap.1Jn 2:8
Means real or genuine as opposed to a copy, a shadow, or an inferior substitute: the actual thing itself.Jhn 6:32Jhn 15:1Heb 8:2
Marks the authentic one over against false or counterfeit rivals, whether the God who is really God, the real light, or genuine worship.Jhn 17:31Th 1:9Jhn 4:23
Means dependable and reliable, and is often paired with faithful to affirm that God's words and judgments will genuinely hold.Rev 19:11Rev 21:5Rev 15:3
ἀλήθειαthe noun "truth" itself, the quality this adjective attributes to a statement, a person, or a thing
Describes a person as honest and reliable, someone whose word can be trusted, rather than naming truth as a thing. It marks a witness or a teacher as one who does not lie.Jhn 7:182Co 6:8Tit 1:13
Rates a specific statement or testimony as accurate, saying that this particular claim or record holds up and matches reality.Jhn 19:35Jhn 21:24Jhn 8:17
Affirms that God himself is truthful and keeps his word even when every human fails, treating truthfulness as a settled trait of his character.Jhn 3:33Rom 3:4
Both
In the very same breath the two pull together: a teacher is praised for teaching God's way in truth, the reality, while being called true, the honest sort who does not bend to please anyone. The noun names the substance taught and the adjective rates the teacher's integrity.Mat 22:16Mrk 12:14
Both back a trustworthy testimony at once: a witness is vouched for as true, the reliable kind, and his witness is said to be in the truth, matching how things really are.3Jn 1:12
Names the reality itself, the truth as a thing you can possess, know, and stand in, not a quality you pin on someone. It is what sets people free, what the Spirit guides into, and what believers are described as belonging to or being sanctified by.Jhn 8:32Jhn 16:13Jhn 17:17
Stands for the whole content of the gospel, the saving message itself, so people can come to it, obey it, be established in it, or turn away from it.Eph 1:13Gal 2:52Th 2:13
Functions as something a person actively does or lives by, paired with verbs of doing and walking, not just something a statement is. People do the truth, walk in the truth, and speak the truth.Jhn 3:211Jn 1:6Eph 4:25
alēthēs in the other biblical languages
אֱמֶתHebrew“truth: faithful”the main Hebrew word behind this idea, but rooted in firmness and reliability, so it leans toward faithfulness and trustworthiness where the Greek leans toward factual accuracy
Works as a legal word for a witness or testimony that is valid and admissible, the courtroom claim that what someone says can stand as proof.Jhn 5:31Jhn 8:14Jhn 8:173Jn 1:12
Marks a thing as real and genuine rather than counterfeit, the authentic article as opposed to a mere copy or appearance.Jhn 6:55
Both
Both certify that a statement or report matches the facts, verified as correct when it is tested.1Ki 10:6Jhn 4:18
Both describe a person as truthful and trustworthy, honest in speech and free from flattery or partiality.Exo 18:21Mat 22:16
Names steadfast reliability, the settled faithfulness of God that can be leaned on, and is regularly paired with covenant loyalty and steadfast love.Gen 24:27Exo 34:6Psa 25:102Sa 2:6
Describes acting toward another person in loyal good faith, dealing kindly and dependably so that a promise is kept.Gen 47:29Jos 2:142Sa 15:20
Stands for truth as a firm, enduring standard, the dependable norm of God's law and word that does not shift.Psa 19:9Neh 9:13Psa 25:5
What scholars say about alēthēs
The adjective is formed with the privative alpha on the root of λανθάνω ("to escape notice, be hidden"), so its etymological force is "not hidden, disclosed," hence real; BDAG and LSJ, however, treat the operative NT sense as "truthful, veracious" (of persons and reports) and "genuine, real" (of things), the antonym in each case being ψευδής. Standard lexica (BDAG s.v. ἀληθής; LSJ) group the occurrences under truthful statements and testimony, honest persons, and genuine things. R.C. Trench (Synonyms of the New Testament, §viii) draws the classic contrast with ἀληθινός: ἀληθής stands opposed to the false (ψευδής), ἀληθινός to the counterfeit or shadowy as against the genuine and archetypal. Bultmann's ἀλήθεια article (TDNT 1:232-251) surveys the Greek background and its interaction with Hebrew אֱמֶת, which the Septuagint regularly renders with this word group; the Johannine concentration of the term reflects that Gospel's forensic interest in reliable witness.
Sources
BDAG, s.v. ἀληθήςlexicon
LSJ, s.v. ἀληθήςlexicon
R.C. Trench, Synonyms of the New Testament, §viiimonograph
R. Bultmann, "ἀλήθεια κτλ.," TDNT 1:232-251dictionary