playbook n.

Middle English pleie, from Old English plega (West Saxon), plæga (Anglian) "quick motion; recreation, exercise, any brisk activity" (the latter sense preserved in swordplay -- Old English sweordplegan -- etc.), from or related to Old English plegan (see play (v.)).

By early Middle English it could mean variously, "a game, a martial sport, activity of children, joke or jesting, revelry, sexual indulgence." Of physical things, "rapid, brisk, or light movement," by 1620s.

Meaning "dramatic performance" is attested by early 14c., perhaps late Old English. Meaning "free or unimpeded movement, liberty and room for action," of mechanisms, etc., is from 1650s. The meaning "activity, operation" (1590s) is behind expressions such as in full play, come into play. The sporting sense of "the playing of a game" is attested from mid-15c.; that of "specific maneuver or attempt" is from 1868.

The U.S. slang meaning "attention, publicity" is by 1929. To be in play (of a hit ball, etc.) is from 1788. Play-by-play in reference to running commentary on a game is attested from 1927. Play on words "pun" is from 1798. Play-money is attested from 1705 as "money won in gambling," by 1920 as "pretend money."

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.