say it: LUHL-uh-bahy
lullaby is a noun meaning "a quiet song intended to lull a child to sleep". It carries 2 recorded senses.
a quiet song intended to lull a child to sleep
the act of singing a quiet song to lull a child to sleep
Forms marked · are formed by the regular rule rather than recorded in the source data. English keeps a few hundred irregulars and the rest follow the pattern, so the rule is right far more often than not — but it is a rule, and the mark says so.
Definitions, synonyms and semantic relations for lullaby come from Princeton University’s WordNet. The pronunciation comes from the CMU Pronouncing Dictionary. Commonness is measured against a corpus of everyday English. Full sources and licences.