Comma Johanneum: A textual variant in 1 John that should be excluded from the text (Gk komma, “a piece, that which is cut off”). The disputed textual variant occurs in 1 John 5:7-8 (“There are three that testify in heaven, the Father, the Word, and the Holy Spirit, and these three are one. And there are three that testify on earth“) and was inserted by Erasmus into his Greek text. It was subsequently included in the King James Version. The words in italics above are not authentic and should be “cut off,” that is, not be included in the NT.
 Arthur G. Patzia; Anthony J. Petrotta. Pocket Dictionary of Biblical Studies (pp. 26-27). Kindle Edition.