A spirit level is a tool with a bubble that shows whether a line is true. Use a spirit level.
The tube is curved and not quite full, so the bubble rises to the highest point. A spirit level should be checked by turning it round, since a bad one lies consistently.
1nounspirit levelA tool with a bubble that shows whether a line is true.
“The spirit level said the whole floor sloped.”
spirit level is a tool.
Practised in Tools & DIY