okay here:
this sentence can be broken down into two:
A. Are there any words?
B. You do not know the meaning of them.
�words �= �them�
If we are to combine these sentences, B will be the subordinating clause.
How? By replacing �them � with a subordinating conjunction �which � and placing it next to �words �
So the longer version of this is:
Are there any words which you do not know the meaning of?
Now, here �s the trick, since �them� is in objective case, there are other several possible sentences:
1. Are there any words which you do not know the meaning of? (which...preposition �of�)
2. Are there are words of which you do not know the meaning? (preposition then which)
3. Are there any words that you do not know the meaning of? (that...preposition �of �)
and
4. Are there any questions you do not know the meaning of? (no conjunction at all but prep should always be at the end)
This is only possible if the pronoun you are replacing is OBJECT PRONOUN
But if it is a SUBJECT PRONOUN the you cannot remove which or that
That is the word which confuses me. (grammatical)
That is the word that confuses me. (grammatical)
That is the words confuses me. (ungrammatical)
The original sentences are:
A. That is the word.
B. IT confuses me. (IT is a subject pronoun)
Hope this helps!
For more info regrding this, I have read it from FOUNDATIONS OF ENGLISH GRAMMAR by Betty Schrampher-Azar
I hope I got her name right.