noun.
A conical mineral deposit, usually calcite or aragonite, built up on the floor of a cavern, formed from the dripping of mineral-rich water.
The Century Dictionary and Cyclopedia
noun.
Carbonate of lime deposited on the floor of a cavern. See stalactite.
the GNU version of the Collaborative International Dictionary of English
noun.
A deposit more or less resembling an inverted stalactite, formed by calcareous water dropping on the floors of caverns; hence, a similar deposit of other material.