Other forms: bookcases
A bookcase is the tall piece of furniture with shelves full of things to read. Upright sides, and boards between them.
The word is one word and it covers everything from a two-shelf unit beside a bed to a wall of oak in a library. A bookshelf is strictly a single shelf, though most people use the two words interchangeably. Fitted bookcases are built into the wall and free-standing ones must be tied to it, since a loaded bookcase is extremely heavy and falls forwards. The books always outgrow it.
1nounbookcaseA piece of furniture with shelves for holding books.
“The bookcase reached almost to the ceiling.”
Also accepted in games: bookshelf
From book + case.
Etymology from Wiktionary, CC BY-SA