the note indicated by the first leger line above the bass staff and the first below the treble staff.
Origin of middle C
First recorded in 1830–40
Dictionary.com Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2019
British Dictionary definitions for middle c
music the note graphically represented on the first ledger line below the treble staff or the first ledger line above the bass staff and corresponding in pitch to an internationally standardized fundamental frequency of 261.63 hertz
Collins English Dictionary - Complete & Unabridged 2012 Digital Edition © William Collins Sons & Co. Ltd. 1979, 1986 © HarperCollins Publishers 1998, 2000, 2003, 2005, 2006, 2007, 2009, 2012