Giddiest

adjective

1. Dizzy, feeling dizzy or unsteady and as if about to fall down.

   "The man became giddy upon standing up so fast."

2. Causing dizziness: causing dizziness or a feeling of unsteadiness.

   "They climbed to a giddy height."

3. Lightheartedly silly, or joyfully elated.

   "The boy was giddy when he opened his birthday presents."

4. Frivolous, impulsive, inconsistent, changeable.