Definition of fastness
- vacationed in their mountain fastness
the amazing fastness with which the boy took his shower had us wondering if he'd used any water
the guerillas retreated to their network of hidden fastnesses deep within the mountains
These example sentences are selected automatically from various online news sources to reflect current usage of the word 'fastness.' Views expressed in the examples do not represent the opinion of Merriam-Webster or its editors. Send us feedback.
before 12th century
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