Merriam-Webster's Collegiate® Dictionary, 11th Edition
DIZZY
I. adjective (dizzier; -est)
Etymology: Middle English disy, from Old English dysig stupid; akin to Old High German tusig stupid Date: before 12th century foolish , silly ,
2. having a whirling sensation in the head with a tendency to fall, mentally confused,
3. causing giddiness or mental confusion , caused by or marked by giddiness, extremely rapid , dizzily adverb dizziness noun
II. transitive verb (dizzied; dizzying)
Date: 1501
to make dizzy or giddy, bewilder , dizzyingly adverb