Origin of the word "facebook"?

Etymonline:

directory listing names and headshots, by 1983, originally among U.S. college students, from face (n.) + book (n.). The social networking Web site of that name (with capital F-) dates from 2004.

It is hard to trace back the noun "facebook" in Google Books (because of "Facebook") but I could trace back to 1988. Here is an excerpt from the book Letting Go: A Parents Guide to Today's College Experience from 1988:

We were supposed to send in a picture to be in the freshman facebook. I didn't want to have my face in the facebook.

@ermanen's etymology is correct, and Harvard definitely had a physical printed book that listed students' names and addresses, but Zuckerberg most likely got the name of his social media site from the printed directory produced by his high school, Phillips Exeter Academy.

Check out this article, where a former Exeter classmate of Zuckerberg says,

"The front cover says "The Photo Address Book," but we all called it "The Facebook" all the time because "The Photo Address Book" was such a mouthful. Everybody called it that."

Also note that the first version of Zuckerberg's site was called "The Facebook".

And here's a fun clip from the movie The Social Network where you hear Harvard students referring to it as "the facebook".

I chanced upon, I think, the earliest mentioned word of Facebook on youtube - Newhart, episode 115 titled "Here's To You Mrs. Loudon," at 1:11 minute, aired September 14, 1987

George Utley: The Beavers are putting out a facebook.
Dick Loudon: facebook??
George Utley: You know, a book of pictures of our faces with our names under them. All the Beavers except me have nicknames ...

YouTube video

The earliest occurrence I've found of the term "face book" to mean a student directory with pictures dates to 1968. An article in the Newark Star-Ledger describes a book with pictures and profiles of 1,500 students at eight women's colleges, put together by editors at Princeton University's student newspaper. The book, according to its editor, Peter G. Brown, was designed to take the "blind" out of blind date.

That might not qualify as the earliest use of "face book," but the article quotes a first year Smith College student as saying every student in her dorm submitted a picture "because the fellows at Princeton have promised to do our student handbook."

True, said Brown [the article continues], the pictures will do double duty. Princeton will publish what he called Smith's 'face book'."

-- "Princeton Opens the Eyes of Its Blind Daters," Newark Star-Ledger, December 6, 1968, p1.

Northwestern University had a "face book" as early as the 1970s. It's mentioned in several articles in the student newspaper. The earliest one I've found is from 1973.

ASG representative Bill Roegel is currently working on the registry, or 'face book' as it is commonly called, which would contain names, photographs, and hometowns, and possibly campus addresses, hobbies, and majors of incoming freshmen.

-- "ASG Rep Plans Freshman Registry for Class of '77," Daily Northwestern, January 30, 1973, p2.

Princeton's own directory of first year students, the Freshman Herald, was referred to informally as "the face book" as early as 1974. A whimsical "Official Princeton Dictionary" in the Daily Princetonian a year later defined "face book" as "n. The Freshman Herald, indispensable reference tool, with the photo of everyone in the class. Makes good reading on a Saturday might." (July 25, 1975, p15.)

I'll bet there are other examples from colleges earlier than 1968.