n. 1 a large floating mass of ice detached from a glacier or ice-sheet and carried out to sea. 2 an unemotional or cold-blooded person. iceberg lettuce any of various crisp lettuces with a freely blanching head. the tip of the iceberg a small perceptible part of something (esp. a difficulty) the greater part of which is hidden.
[ prob. f. Du. ijsberg f. ijs ice + berg hill ]