bottlebrush

noun

1. A cylindrical brush on a thin shaft that is used to clean bottles.
2. Any of various trees or shrubs of the myrtle family, especially of the genera Callistemon and Melaleuca, native to Australia and adjacent areas, having spikes of flowers with numerous conspicuous stamens.
3. An uncommon cave formation resulting from a rise in water level such that a stalactite becomes immersed in water that is supersaturated with calcium carbonate, causing the stalactite to become coated with pool spar.