The King James Version (KJV) was translated into English in 1611 A.D. at the request of King James of England. Therefore, it is also known as the Authorized Version. As you would expect, many words which were common then are either not in general use today, or have taken on a variation in meaning. When you are not sure what a word means, check it out in a standard Dictionary and/or in a Dictionary of Bible words.
Besides unusual words, grammatic structure and word endings may seem odd to the modern reader. Today, languages such as German, Spanish, and French retain structures which are absent from modern English. Word forms & endings may vary depending on word usage (eg., verb tense), gender (male or female), and number (singular or plural). Modern English also has word variations. For example note the following variations in the verb "to be" in modern english:
Present tense Past tense Past perfect I am I was I have been You are You were You have been He is He was He has been We are We were We have been You (pl.) are You (pl.) were You (pl.) have been (pl. = plural) They are They were They have been
Here are the same variations of the verb "to be" in KJV english:
Present tense Past tense Past perfect I am I was I have been Thou art Thou wert* Thou hast been He is He was He hath been We are We were We have been You (ye) are You (ye) were You (ye) have been They are They were They have been *Sometimes: "wast" or "wert".
Notice also the variation in the verb "to have" in the above example.
Notice also that "thou" takes various forms depending on its grammatical usage:
See, there really is no reason to stumble over the "thee's and thou's". But what about the "-eth's"? In the KJV english, some verbs have suffixes (endings) which vary depending on word usage. For example:
The verb "to say"- Present tense Past tense Past perfect I say I said I have said Thou sayest Thou saidst Thou hast said He saith* He said He hath said We say We said We have said You (ye) say You said You have said They say They said They have said *Saith- pronounce as "seth" or "say-eth". The verb "to do"- Present tense Past tense Past perfect I do I did I have done Thou doest* Thou didst Thou hast done He doeth** He did He hath done We do We did We have done You (ye) do You did You have done They do They did They have done *Sometimes: dost (pronounce as "dust"), or doest (pronounce as "doo-est"). **Sometimes: doth (pronounce as "duth"), or doeth (pronounce as "doo-eth").
I hope you see that the structure of KJV English is really not so mysterious. In fact, it is not really so different from the modern language which we use everyday. As you become familiar with them, you may find that the additional word forms and endings may actually enhance the meaning of a passage, by giving you grammatic clues for connecting the various pieces of a passage.
For Definitions of more than 500 archaic words used in the KJV Bible, see The King James Bible Companion. (Also accessed via the Glossary button on the button bar.)