The spelling of the phrase "hath fit" may seem peculiar to some, but it is a common archaic way of saying "has a fit". The letters "hath" are a contraction of "has" and "fit" refers to a sudden outburst of emotion. The pronunciation of "fit" in this phrase is /fɪt/, which means it sounds like "fit" as in "out of shape" with a short "i" sound. Though not commonly used today, "hath fit" can be found in literature from past centuries.
The phrase "hath fit" does not have a specific etymology of its own, as it is a combination of two separate words: "hath" and "fit".
1. "Hath" is the archaic third-person singular present tense of "have", mainly used in Early Modern English. It is derived from the Old English word "hæfþ", which means "he/she/it has". Eventually, "hath" fell out of common usage and was replaced by "has" in most English dialects.
2. "Fit" is a noun that originated from the Old English word "fit", which means "a seizure, paroxysm, or sudden attack". Over time, "fit" also came to mean "a sudden and impulsive change of mind or mood". The verb form of "fit" describes the action of experiencing a fit or seizure.