Someone or something that is frivolous or impulsive.

(Britain, agriculture, veterinary medicine) Synonym of gid (“a disease caused by parasitic infestation of the brain by tapeworm larvae”)

(transitive) To make (someone or something) dizzy or unsteady; to dizzy.

(intransitive) Become dizzy or unsteady.

Feeling a sense of spinning in the head, causing a perception of unsteadiness and being about to fall down; dizzy.

Causing or likely to cause dizziness or a feeling of unsteadiness.

Moving around something or spinning rapidly.

(by extension) Giddy is an adjective that describes someone who is joyfully elated and overcome with excitement or happiness.