Syllable division and stress derived from spelling — this word is not in the pronouncing dictionary, so no phonetic transcription is shown rather than a guessed one.
two-by-four is a noun meaning "a timber measuring (slightly under) 2 inches by 4 inches in cross section". It carries one recorded sense.
a timber measuring (slightly under) 2 inches by 4 inches in cross section
Definitions, synonyms and semantic relations for two-by-four come from Princeton University’s WordNet. Commonness is measured against a corpus of everyday English. Full sources and licences.