Concise Bible Dictionary:

A thin skin prepared for receiving writing. It is much more durable than papyrus. The great majority of the early copies of the scriptures that are extant are on parchment and have thus been preserved to us (2 Tim. 4:1313The cloke that I left at Troas with Carpus, when thou comest, bring with thee, and the books, but especially the parchments. (2 Timothy 4:13)).

Strong’s Dictionary of Greek Words:

of Latin origin ("membrane"); a (written) sheep-skin
KJV Usage:

From Manners and Customs of the Bible:

Parchment books were rolled around a stick or cylinder, and, if very long, around two cylinders, from the two extremities. There is in the public library at Cambridge, England, an ancient manuscript roll of the Pentateuch. It is made of goats’ skins dyed red, and measures forty-eight feet in length by about twenty-two inches in breadth. As the book of Leviticus and a part of Deuteronomy are wanting, it is calculated that the original length could not have been far from ninety feet. It consists of thirty-seven different skins, and contains one hundred and seventeen different columns of writing. These columns correspond to the pages of our books, are each about four inches wide, and contain from forty to fifty lines apiece. This manuscript is undoubtedly very ancient, though its date cannot now be ascertained. It was obtained by the Dr.. Buchanan from the black Jews in Malabar.
The celebrated Samaritan Pentateuch is the oldest manuscript of which we have any knowledge. It consists of twenty-one skins of unequal size, most of which contain six, but some only five, columns. The columns are thirteen inches deep and seven and a half wide. Each contains from seventy to seventy-two lines, and the entire roll has one hundred and ten columns.
Ancient rolls were sometimes encased in a cover, which was more or less ornamented, and on which the title was sometimes written. This case corresponded to the envelopes in which their letters were put. See note on Nehemiah 6:55Then sent Sanballat his servant unto me in like manner the fifth time with an open letter in his hand; (Nehemiah 6:5) (#381). Some commentators think that this outside cover, with ifs title, is what is referred to in Psalm 40:77Then said I, Lo, I come: in the volume of the book it is written of me, (Psalm 40:7): “In the volume of the book it is written of me.” Others suppose that reference is made in that text to a small strip of parchment which was attached to each roll, and contained the title, so that the nature of the contents could be ascertained without the trouble of unrolling.
This style of book is often referred to in the Bible. See Ezra 6:1-21Then Darius the king made a decree, and search was made in the house of the rolls, where the treasures were laid up in Babylon. 2And there was found at Achmetha, in the palace that is in the province of the Medes, a roll, and therein was a record thus written: (Ezra 6:1‑2); Jeremiah 36:2,23,292Take thee a roll of a book, and write therein all the words that I have spoken unto thee against Israel, and against Judah, and against all the nations, from the day I spake unto thee, from the days of Josiah, even unto this day. (Jeremiah 36:2)
23And it came to pass, that when Jehudi had read three or four leaves, he cut it with the penknife, and cast it into the fire that was on the hearth, until all the roll was consumed in the fire that was on the hearth. (Jeremiah 36:23)
29And thou shalt say to Jehoiakim king of Judah, Thus saith the Lord; Thou hast burned this roll, saying, Why hast thou written therein, saying, The king of Babylon shall certainly come and destroy this land, and shall cause to cease from thence man and beast? (Jeremiah 36:29)
; Ezekiel 2:9; 3:1-29And when I looked, behold, an hand was sent unto me; and, lo, a roll of a book was therein; (Ezekiel 2:9)
1Moreover he said unto me, Son of man, eat that thou findest; eat this roll, and go speak unto the house of Israel. 2So I opened my mouth, and he caused me to eat that roll. (Ezekiel 3:1‑2)
; Zechariah 5:1-21Then I turned, and lifted up mine eyes, and looked, and behold a flying roll. 2And he said unto me, What seest thou? And I answered, I see a flying roll; the length thereof is twenty cubits, and the breadth thereof ten cubits. (Zechariah 5:1‑2); 2 Tim. 4:1313The cloke that I left at Troas with Carpus, when thou comest, bring with thee, and the books, but especially the parchments. (2 Timothy 4:13) and probably Revelation 5:11And I saw in the right hand of him that sat on the throne a book written within and on the backside, sealed with seven seals. (Revelation 5:1), though some commentators think that a book of leaves is there meant.