Colloquial reduplicated form, common in spoken Mandarin. Built from 晕乎 (yūnhū) by AABB reduplication, which softens it and adds a 'kind of, sort of' quality — you're not collapse-dizzy, just fuzzy-headed. Often follows a 的 when used as a predicate.
mistakes
晕 has two readings: yūn (dizzy, faint) and yùn (motion sickness, halo). In 晕晕乎乎 the meaning is 'dizzy/groggy', so use yūn. 晕车 (yùnchē, motion sick) uses yùn. Same character, different jobs.
