notebook n.

c. 1300, "a song, music, melody; instrumental music; a bird-song; a musical note of a definite pitch," from Old French note and directly from Latin nota "letter, character, note," originally "a mark, sign, means of recognition," which traditionally has been connected to notus, past participle of noscere "to come to know," but de Vaan reports this is "impossible," and with no attractive alternative explanation, it is of unknown origin.

Meaning "notice, attention" is from early 14c.; that of "reputation, fame" is from late 14c. From late 14c. as "mark, sign, or token by which a thing may be known." From late 14c. as "a sign by which a musical tone is represented to the eye." Meaning "a brief written abstract of facts" is from 1540s; meaning "a short, informal written communication" is from 1590s. From 1550s as "a mark in the margin of a book calling attention to something in the text," hence "a statement subsidiary to the text adding or elucidating something." From 1680s as "a paper acknowledging a debts, etc." In perfumery, "a basic component of a fragrance which gives it its character," by 1905.

Middle English bok, from Old English boc "book, writing, written document," generally referred (despite phonetic difficulties) to Proto-Germanic *bōk(ō)-, from *bokiz "beech" (source also of German Buch "book" Buche "beech;" see beech), the notion being of beechwood tablets on which runes were inscribed; but it may be from the tree itself (people still carve initials in them).

Latin and Sanskrit also have words for "writing" that are based on tree names ("birch" and "ash," respectively). And compare French livre "book," from Latin librum, originally "the inner bark of trees" (see library).

The sense gradually narrowed by early Middle English to "a written work covering many pages fastened together and bound," also "a literary composition" in any form, of however many volumes. Later also "bound pages," whether written on or not. In 19c. it also could mean "a magazine;" in 20c., a telephone directory.

The use of books or written charters was introduced in Anglo-Saxon times by the ecclesiastics, as affording more permanent and satisfactory evidence of a grant or conveyance of land than the symbolical or actual delivery of possession before witnesses, which was the method then in vogue. [Century Dictionary] 

From c. 1200 as "a main subdivision of a larger work." The meaning "libretto of an opera" is from 1768. A betting book "record of bets made" is from 1812. The meaning "sum of criminal charges" is from 1926, hence slang phrase throw the book at (1932). Book of Life "the roll of those chosen for eternal life" is from mid-14c. Book of the month is from 1926. To do something by the book "according to the rules" is from 1590s.