Definition of "iceberg"

(obsolete) The seaward end of a glacier.

A huge mass of ocean-floating ice which has broken off a glacier or ice shelf  examples

(US, slang) An aloof person.

(figuratively, after an adjective) An impending disastrous event whose adverse effects are only beginning to show, in reference to one-tenth of the volume of an iceberg being visible above water.  quotations  examples