Dizzy, feeling dizzy or unsteady and as if about to fall down.
The man became giddy upon standing up so fast.
Causing dizziness: causing dizziness or a feeling of unsteadiness.
They climbed to a giddy height.
Lightheartedly silly, or joyfully elated.
The boy was giddy when he opened his birthday presents.
Frivolous, impulsive, inconsistent, changeable.