1.  alethes = true ¹ (as contrasted with what is false). Hence, used of God (John 3:33) in that He cannot lie (see also John 5:31; 8:13). The opposite of a lie. Greek apseudes. Titus 1:2. Compare John 4:18. 1John 2:27.

 2.  alethinos = very.¹ French véritable: that is to say, genuine, real, substantial, as contrasted with that which is fictitious, unreal, shadowy, or symbolical. Hence, alethinos is that which has truth for its base and is all that
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  ¹ See notes on the Structure of the Gospel of John.

it claims to be (John 6:32; 15:1). See 1Thessalonians 1:9. Hebrews 8:2; 9:24.
 
 3.  gnesios = legitimate. Spoken of children. Occurs only in Philippians 4:3. 1Timothy 1:2. Titus 1:4. With Article = sincerity (2Corinthians 8:8). The Adverb gnesios = naturally, occurs only in Philippians 2:20.
 
 4.  pistos = faithful. A verbal Adjective, from peitho = to persuade, and Passive to be persuaded and convinced. Hence, believing, faithful, trustworthy. Translated "true" in 2Corinthians 1:18. 1Timothy 3:1. See Ap. 150. III.