say it: WIND-fawl
windfall is a noun meaning "fruit that has fallen from the tree". It carries 2 recorded senses.
fruit that has fallen from the tree
a sudden happening that brings good fortune (as a sudden opportunity to make money)
“the demand for testing has created a boom for those unregulated laboratories where boxes of specimen jars are processed like an assembly line”
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 windfall 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.