from The American Heritage® Dictionary of the English Language, 4th Edition
- n. A small evident part or aspect of something largely hidden: afraid that these few reported cases of the disease might only be the tip of the iceberg.
from Wiktionary, Creative Commons Attribution/Share-Alike License
- n. Only the beginning; just a small indication of a larger possibility; a problem is much bigger than it seems
tip + iceberg. Floating icebergs have a significant proportion of their mass below the surface of the water. (Wiktionary)