Black Slab in 2001: a Space Odyssey
Puzzle 19 of Movie Props Pack
Question is: Black Slab in 2001: a Space Odyssey
and the answer is: MONOLITH
Word Meaning:
MONOLITH — (also attributively) A large, single block of stone which is a natural feature; or a block of stone or other similar material used in architecture and sculpture, especially one carved into a monument in ancient times.
Definitions from Wiktionary.