From Longman Dictionary of Contemporary Englishmikemike1 /maɪk/ noun [countable] 
informalx-ref a microphone → open mike
informalx-ref a microphone → open mikeExamples from the Corpus
mike• Keyboards, drum machines and mikes filled most of the available space.• So the second morning we all went out again only this time wearing radio mikes as well.• She wanders the stage, mike in hand like Betty Carter, often hovering over one of her accompanists, particularly Terrasson.• So this, this hooks in here, okay, for the mikes and the mikes are just right here.• In the middle of reading the Arts Calendar he switched the mike off to scream and curse.• The mike clipped to the inside of his cuff.mikemike2 verb → mike somebody ↔ up→ See Verb tableExamples from the Corpus
mike• All the instruments are miked.MikeMike noun → for the love of MikeOrigin mike1 (1900-2000) microphone 