Syllable division derived from spelling — this word is not in the pronouncing dictionary, so no phonetic transcription is shown rather than a guessed one.
hair's-breadth is a noun meaning "a very small distance or space". It carries one recorded sense.
a very small distance or space
“they escaped by a hair's-breadth”
“they lost the election by a whisker”
Definitions, synonyms and semantic relations for hair's-breadth come from Princeton University’s WordNet. Commonness is measured against a corpus of everyday English. Full sources and licences.