Why are there Italicized Words in the King James Bible?
Some words in the Authorized King James Version of the Bible are italicized. These are words that were not found in the translated manuscripts but were added by the King James translators from 1604 to 1611. To show the reader the added words the translators set them in smaller Roman type. In later Bible editions the small Roman type was changed to italics.
Many times a phrase cannot be translated literally from one language to another. There may not be a corollary word or expression in English.
The Old Testament was mostly written in Hebrew, with some parts written in Aramaic. The New Testament was written in Greek. So that we could have a clearer and more readable Bible version in English the King James translators added English words where appropriate. The italicized words let us know that they were not in the available manuscripts.
For example, here is Psalm 18:3 without the italicized words:
I will call upon the LORD, to be praised: so shall I be saved from mine enemies.
Here is the same verse, but with the italicized words:
I will call upon the LORD, who is worthy to be praised: so shall I be saved from mine enemies.
There is one other reason for italicized words. The translators had New Testament Greek manuscripts which included words that other Greek manuscripts did not. In those cases the translators had evidence from other languages to include the words, or they had strong evidence to believe that the words had been mistakenly omitted by a copyist, so they added those words also.