The phrase "hath nightmare" refers to having a bad dream or experiencing a frightening or disturbing dream while sleeping. There are a number of synonyms for this phrase, including "had a bad dream," "suffered from a nightmare," "experienced a frightening dream," "endured a terrifying dream," and "had a disturbing dream." All of these phrases convey a similar meaning and can be used interchangeably to describe a negative dream experience. If you want to use a more informal or colloquial expression, you might use phrases like "had a freaky dream," "had a scary dream," or "had a creepy dream".