Bing found the following results
Online collaborative music notation software - Flat
Flat Definition & Meaning - Merriam-Webster
FLAT Definition & Meaning | Dictionary.com
FLAT | English meaning - Cambridge Dictionary
FLAT | definition in the Cambridge Learner’s Dictionary
Flat - Definition, Meaning & Synonyms | Vocabulary.com
FLAT definition and meaning | Collins English Dictionary
FLAT definition in American English | Collins English Dictionary
flat - WordReference.com Dictionary of English
Flat Definition & Meaning | Britannica Dictionary