From Longman Dictionary of Contemporary Englishsofa bedˈsofa bed noun [countable] DHFa sofa that has a bed inside that can be folded out
Examples from the Corpus
sofa bed• The third or fourth bed may be a sofa bed in some cases.• People who live near a corner where another so-and-so has abandoned a grotty sofa bed.• She helped him to his sofa bed in the living room, and he still did not wake up. 