Ill-naturedly is a word that describes a negative attitude or disposition towards others. There are several synonyms that can be used in place of ill-naturedly, such as:
1. Maliciously - describing someone who is intentionally causing harm or acting with ill intent.
2. Cynically - describing someone who views others with a lack of trust or belief in their motives.
3. Spitefully - describing someone who is seeking to hurt others out of malice or revenge.
4. Sourly - describing someone who is in a bad mood or displaying a negative attitude towards others.
5. Bitterly - describing someone who is full of resentment or anger towards others.
Overall, there are several words that can be used in place of ill-naturedly to describe someone who is displaying a negative attitude towards others.