Adam Clarke on Ecclesiastes 1:1

The words of the Preacher - Literally, "The words of Choheleth, son of David, king of Jerusalem." But the Targum explains it thus: "The words of the prophecy, which Choheleth prophesied; the same is Solomon, son of David the king, who was in Jerusalem. For when Solomon, king of Israel, saw by the spirit of prophecy that the kingdom of Rehoboam his son was about to be divided with Jeroboam, the son of Nebat; and the house of the sanctuary was about to be destroyed, and the people of Israel sent into captivity; he said in his word - Vanity of vanities is all that I have labored, and David my father; they are altogether vanity." The word קהלת Koheleth is a feminine noun, from the root קהל kahal, to collect, gather together, assemble; and means, she who assembles or collects a congregation; translated by the Septuagint, ekklhsiasthv, a public speaker, a speaker in an assembly; and hence translated by us a preacher. In my old MS. Bible it is explained thus: a talker to the peple; or togyder cleping.