From Longman Dictionary of Contemporary Englishspirit levelˈspirit ˌlevel noun [countable] especially British English 
TITZa tool used for testing whether a surface is level
TITZa tool used for testing whether a surface is levelExamples from the Corpus
spirit level• The hinge itself must also be horizontal, using a spirit level.• Simply line up the shelf in position, using a spirit level, before permanent fixing for a really professional result.• Tap in place with the club hammer handle and check with a spirit level as work progresses. 