Augustine spoke of Latin MSS (copies of scriptures in Latin) that has 'sermo' instead of 'verbum' in John 17:17 and John 1:1 in his Tractate 108:

Finally, He proceeds, and doing so fails not to suggest the same with increasing clearness: Your speech (sermo) is truth. What else did He mean than I am the truth? For the Greek Gospel has λόγος, which is also the word that is found in the passage where it is said, In the beginning was the Word, and the Word was with God, and the Word was God. And that Word at least we know to be the only begotten Son of God, which was made flesh, and dwelt among us. Hence also there might have been put here as it actually has been put in certain copies, Your Word is truth; just as in some copies that other passage is written, In the beginning was the speech. But in the Greek without any variation it is λόγος in both cases. The Father therefore sanctifies in the truth, that is, in His own Word, in His Only begotten, His own heirs and His (the Son's) co-heirs.

What does the Latin word 'sermo' convey that 'verbum' does not in John 17:17 and John 1:1?