Grammar Tips: Bad vs. Badly
“I felt badly” or “I felt bad”? The quick answer is that you should not say “I felt badly” unless you are describing a problem with your fingers or your sense of touch–the way in which you perform the physical act of feeling. Here’s why:
Badly is an adverb, meaning it modifies a verb, adjective, or another adverb. In our example sentence, “I felt badly,” the verb is “felt,” meaning that badly modifies the way you feel–not your emotional state, but the literal action of moving your fingers. Bad, on the other hand, is an adjective, meaning it modifies a noun. In our example sentence, the noun is “I,” meaning that bad modifies something about me–in this case, my emotional state. That’s why it’s correct to say “I felt sad” and not “I felt sadly.”
At the same time, there are occasions when you should use the word “badly,” namely when the verb you employ suggests action rather than a state of being. “The actor performed badly” or “the discussion went badly,” for instance, are correct because performed and went are both action verbs, requiring an adverb to modify them.
It might surprise some of our readers to learn that this is a matter of great debate, dating back to at least this New York Times article from 1879. Check it out for a far more elaborate, tongue-in-cheek explanation of the grammatical rules informing these phrases.