Source : Webster's Revised Unabridged Dictionary (1913)

Mono- \Mon"o-\, Mon- \Mon-\ [Gr. ?.]
   A prefix signifying one, single, alone; as, monocarp,
   monopoly; (Chem.) indicating that a compound contains one
   atom, radical, or group of that to the name of which it is
   united; as, monoxide, monosulphide, monatomic, etc.