etymology - What is the origin of がち in 病気がち?

I know from my dictionary that 病気がち means "proneness to being ill". 病気 just means illness, so where does the がち come from?

My research so far: I think がち might be the ます-stem of the verb 勝つ. The dictionary supports this hypothesis as it lists 勝ち as a suffix meaning "apt to do; tend to do (used to describe a negative tendency)". It also lists 涙勝ち as an "archaism" for "prone to crying" which further supports my hypothesis.

I have the following questions:

1. Is 勝つ really the origin of がち in 病気がち?


2. Why is a very positive verb such as 勝つ used to describe "being prone to something" in a negative way?


3. Are there any other examples of 勝つ being used in a negative way?


4. Are there any similar commonly used words ending in 勝ち?

Answer

1. Is 勝つ really the origin of がち in 病気がち?

Yes I think so. But in modern Japanese this suffix is usually written in hiragana.

2. Why is a very positive verb such as 勝つ used to describe "being prone to something" in a negative way?

In modern Japanese it mainly means to win, but 勝つ also means to outweigh or to outperform. Such ～がち suffix survives mainly in some fixed phrases. I think ～がち is not necessarily negative, as seen in the examples below.

3. Are there any other examples of 勝つ being used in a negative way?


4. Are there any similar commonly used words ending in 勝ち?

Here are some common phrases that are safely usable in modern Japanese.

• ～しがち: (na-adj) tend to do ～ (perhaps this is the most common example)


• ありがち: (na-adj) common, frequently seen (it does not have negative connotations)


• 荷が勝つ: (idiom) ～ is too much load (for someone)


• 伏し目がち: (na-adj) with eyes downcast


• 赤みがかった(色)/青みがかった(色): reddish/blueish (color)

Theoretically, I think がち can be used with any action verbs, and you can find some examples in this list (note that these are from relatively old novels). But がち sounds fairly literary today if used outside of fixed phrases.