Greek- what's the difference between Ιησοῖ, Ιησούς, and Ιησού?

Question

I've been looking through the Septuagint and NT Greek manuscripts online and seen these different forms of the name for both Joshua and Jesus. Can someone please explain to me the differences?

Answer 1

This is really a rather elemental question about language, there is nothing special about this name. I would caution you not to make too much of what you find in the Greek manuscripts without actually learning Greek. Learning another language is more than just substituting vocabulary words. There are grammar patterns, ranges of semantic meaning, idioms, and even different logic that you will miss just looking at words. Worse yet, you won't know what you're missing and might easily come to totally false results. You are far more likely to come to wrong conclusions by applying your English language assumptions to a language that does not play by the same rules than if you'd just used a translation in the language you know.

Greek words use different endings depending on how they are used in a sentence. This is just the way the grammar works, indicating person, tense, voice, mood, case, number, gender, or degree. In this case Ἰησοῦς is the lexical form (or root word) and all the other forms are contextual variations based on its use in a sentence.

Answer 2

@Caleb makes the assertion that Ιησους is the Greek "lexical form (or root word)". This indeed might be conventional wisdom and what is found in textbooks and I understand the impetus for this claim, given Ιησους is the source of the standardized Western Jesus. But, for example, Jesu is still used today in German, which is based on the Latin Iesu. So I think it is more accurate, if not easier for the OP (diego b) to understand, that Ιησου (the Aramaic Yeshu) is technically the name that has been imported into Greek and is the "root". The Jewish translators of the Septuagint and the NT authors (see Note 1) appended to or changed the ending of Ιησου accordingly, for nominative, accusative and dative cases (Ιησοι, LXX-only), but left Ιησου alone and appended nothing for vocative (I think this is telling), dative, or genitive.

I'm aware, as documented by Origen, that Aquila used Ιησουα (the Hebraic Yeshua) in his Septuagint recension (see Origen's Hexapla notes on Deuteronomy 1:38); however, this is evidently an exceptional case and I am unaware of evidence that shows how Aquila proceeded to decline this unique transcription.

To briefly answer the OP:

• Iesous (nominative case, indicating subject)
• Iesoun (accusative case, indicating direct object)
• Iesoi (dative case, indicating indirect object)
• Iesou (multiple cases: also dative; plus genitive case, indicating possession; and vocative case, used when addressing someone)

See, for example, Georg Winer's A Greek Grammar of the New Testament (1825; transl. Stuart and Robinson), p. 40.

Notes

1. In the early NT papyri we don't see this name, in all its case forms, being fully spelled out, but rather presented as "nomina sacra" abbreviations: Ις, Ιυ, Ιν, etc. The declined forms are inferred by the final letter of these contractions. (Speculation: perhaps the dative form Ιησοι was not used in the NT to avoid use of the contracted form Iι [double-iota], which may have been deemed problematic for some reason by authors/copyists.)