water ballast
A weight in the form of seawater that can be let or pumped into a ballast tank within…A weight in the form of seawater that can be let or pumped into a ballast tank within a vessel when required.
Meaning
1 senses(uncountable)A weight in the form of seawater that can be let or pumped into a ballast tank within a vessel when required.
Lessons for this word
1 lessons- A1Countable and uncountable nouns — Because it can be uncountable