Jhn 18:20 I spake openly to the world; I ever taught in the synagogue, and in the temple, whither the Jews always resort; and in secret have I said nothing.
I proclaimed frankness in public. Not only did I always teach in the assembly and the temple where all the Jews assembled, but I also proclaimed nothing in hiding.
The Greek word translated as "openly" is not an adverb in form. It is a noun, meaning "freedom of speech." Christ is saying that he urged all people to be open and honest, not just that he himself was.
The Greek word translated as "always" is from the Greek text used by the translators of the KVJ. In the Greek sources used today, the word is "all" and many modern translations such as NIV have it correctly.
The last phrase here is a little misleading. Christ did teach in parables (Mat 13:13) and explained those parables privately to his followers (Mar 4:11). Most recently (Jhn 16:25), he made a point of being more candid with his followers. So he did "teach" in private. So was he lying here?
He makes a change of verb in his "not only/but also" construction. He goes from the word for teach (didaskô) to the the Greek word translated in KJV as "spake" and "said", laleô. This word has two meanings. One is a very informal, causal form of speech, which we might call "prattle" or "chatting." The other is more series, proclamations of an oracle. The fact that the Greeks used the same word for both of these things says something about how seriously they really took oracles, but that is a separate issue.
As my work has gone on, I have come to the conclusion that Christ uses the word laleo primarily in the later sense, meaning "to proclaim." He uses a couple of other much, much more common verbs (lego, eipon) to refer to simply speaking. He uses laleo specifically to describe his proclamations. I have made this distinction before and in this verse we see why it is important to see this.
While Christ may teach or speak about certain things in private, he makes no proclamations in private. He is being asked by the high priest here specifically about his "doctrine," that is, his proclamations. He makes no secret about those. He has discussed and debated them openly with the scribes and the Pharisees since the beginning, especially the areas where he disagrees with the common approach.
λελάληκα (1st sg perf ind act) "Spake" is from laleô (laleo), which means "to talk," "to speak" "to prattle", "to chat," and [for oracles] "to proclaim." It also means "chatter" as the opposite of articulate speech.
συναγωγῇ "The synagogue" is from sunagôgê (synagoge), which means a "bringing together", "assembly", "place of assembly", "contracting", "collection", "combination", "conclusion," and "demonstration." It comes from a Greek word Christ uses commonly, sunagô, to mean "gather" or "bring together."
καὶ ""And" is from kai, which is the conjunction joining phrases and clauses, "and," or "but." After words implying sameness, "as" (the same opinion as you). Used in series, joins positive with negative "Not only...but also." Also used to give emphasis, "even", "also," and "just."
συνέρχονται (3rd pl pres ind mp) "Resort" is from synerchomai, which means "get together", "come together", "assemble", "meet", "meet in battle," and "band together." Of things, it means "to be joined in one." Of events, it means "to concur" and "to happen together."
καὶ "And" is from kai, which is the conjunction joining phrases and clauses, "and," or "but." After words implying sameness, "as" (the same opinion as you). Used in series, joins positive with negative "Not only...but also." Also used to give emphasis, "even", "also," and "just."
ἐλάλησα (1st sg aor ind act) "I said" is from laleô (laleo), which means "to talk," "to speak" "to prattle", "to chat," and [for oracles] "to proclaim." It also means "chatter" as the opposite of articulate speech.