Meaning of BALLAST in English

BALLAST

bal ‧ last /ˈbæləst/ BrE AmE noun [uncountable]

[ Date: 1500-1600 ; Origin: Probably from Low German ]

1 . heavy material that is carried by a ship to make it more steady in the water

2 . material such as sand that is carried in a ↑ balloon so that it can be thrown out to make it rise

3 . a layer of broken stones that a road or railway line is built on

Longman Dictionary of Contemporary English.      Longman - Словарь современного английского языка.