(1):

(superl.) Causing, or tending to cause, giddiness or vertigo.

(2):

(v. t.) To make dizzy or giddy; to give the vertigo to; to confuse.

(3):

(superl.) Having in the head a sensation of whirling, with a tendency to fall; vertiginous; giddy; hence, confused; indistinct.

(4):

(superl.) Without distinct thought; unreflecting; thoughtless; heedless.