Rhema is just the root word.
rhēmatos is the spoken word, statement, someone saying, or utterance, and appears in only 7 places.
So what?
Rhema appears here
Romans 10:8
8 But what saith it? The
word is nigh thee, even in thy mouth, and in thy heart: that is, the
word of faith, which we preach;
Romans 10:17
17 So then faith cometh by hearing, and hearing by the
word of God.
Romans 10:18
18 But I say, Have they not heard? Yes verily, their sound went into all the earth, and their
words unto the ends of the world.
The Holy Bible: King James Version (Electronic Edition of the 1900 Authorized Version.; Bellingham, WA: Logos Research Systems, Inc., 2009).
There is nothing particularly significant in its use
rhematos appears here
Matthew 26:75
75 And Peter remembered the word of Jesus, which said unto him, Before the cock crow, thou shalt deny me thrice. And he went out, and wept bitterly.
Mark 14:72
72 And the second time the cock crew. And Peter called to mind the word that Jesus said unto him, Before the cock crow twice, thou shalt deny me thrice. And when he thought thereon, he wept.
Luke 2:17
17 And when they had seen it, they made known abroad the saying which was told them concerning this child.
Luke 9:45
45 But they understood not this saying, and it was hid from them, that they perceived it not: and they feared to ask him of that saying.
Luke 20:26
26 And they could not take hold of his words before the people: and they marvelled at his answer, and held their peace.
Acts 11:16
16 Then remembered I the word of the Lord, how that he said, John indeed baptized with water; but ye shall be baptized with the Holy Ghost.
Romans 10:17
17 So then faith cometh by hearing, and hearing by the word of God.
The Holy Bible: King James Version (Electronic Edition of the 1900 Authorized Version.; Bellingham, WA: Logos Research Systems, Inc., 2009), Mt 26:75–Ro 10:17.