say it: MA-stur-mahynd
mastermind is a noun and verb meaning "someone who creates new things". It carries 3 recorded senses.
plan and direct (a complex undertaking)
“he masterminded the robbery”
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 mastermind 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.