The opposite of a euphemism is a dysphemism or cacophemism.
Dysphemism is a figure of speech which is defined as the use of disparaging or offensive expressions instead of inoffensive ones... of negative expressions instead of positive ones. A speaker uses them to humiliate or degrade the disapproved person or character. Dysphemism examples may be classified according to the following types.
- Dysphemistic Epithets: animal names are used, like “pig, bitch, rat, dog or snake”.
- Homosexual Dysphemism: these terms are used regarding homosexuality like, “gay, faggot and queer”.
- Synecdoche: it is used to describe something as a whole like, “she is a prick.”
etc. (from Literary Devices)
An example: "Whatever else is unsure in this stinking dunghill of a world a mother’s love is not… (The Portrait of an Artist as a Young Man by James Joyce)