badly

"Badly" tells us how something is done, and it usually signals that the result is poor. If a chef is distracted, they might prepare a dish badly. So in this use it works as the opposite of "well." It also signals intensity, often in phrases like "badly needed" or "badly wanted," meaning "very much."

Just be careful with linking verbs: with states and temporary feelings, we normally use the adjective form, as in "I feel bad" rather than "I feel badly." The adverb is less common there and can sound nonstandard.

"Badly" is a versatile adverb that usually tells us about quality or severity, and sometimes about intensity of need or emotion. It most commonly modifies verbs, as in "The team played badly and lost the game." It can also modify adjectives or participles to show degree, as in "The house was badly damaged by the storm."

The word can be tricky with linking verbs like feel, seem, or smell. In those constructions, English usually prefers the adjective "bad" for the predicate: "I feel bad about the mistake." Using "badly" there often sounds awkward or incorrect unless you mean the manner of the feeling itself.

Beyond negative outcomes, "badly" is frequently used to show a strong desire or pressing need. When you "badly need" something, you need it intensely. It also often describes the impact of an injury or trouble, as in "badly hurt" or "badly injured." These uses show that a situation is intense, harmful, or far from ideal. It's a small word that carries a lot of emotional and descriptive force.