The word desperately is an adverb.
Adverbs are words that modify verbs, adjectives, or other adverbs, providing more detail about how something is done. In the case of ‘desperately,’ it describes the manner in which an action is performed, suggesting that it is done with a sense of urgency, hopelessness, or intensity. For example, in the sentence ‘She searched desperately for her lost keys,’ the adverb ‘desperately’ conveys that her search is filled with desperation.