womens jackets canada Has its meaning become diluted

Has its meaning become diluted

While looking into an answer for Sick and tied and sick and tired, I stumbled across the idiom fit to be tied which according to thefreedictionary means angry and agitated. As if needing to be restrained.

A second search turned up that this refers to the practice of bounding uncontrollable, dangerous people into strait-jackets. How did we make the leap from crazy and uncontrollable to the general usage today of ticked off? Or is my understanding of general usage today incorrect? Is it common for these phrases to become so watered-down over time?

You are correct about the current usage. You would not use it to refer to a mental patient in the technical sense, but apparently it was at one time acceptable to do so. I would have thought that the idiom started life in the angry and agitated sense, but there is one old 1804 citation that I found via an ngrams search which uses the second sense, apparently without irony. I do not know when the newer sense of the phrase took over, but it was certainly in use about 100 years after that first example.

Mad itself seems to have followed the same path. The earliest citations in the OED refer to the mental disease aspect, and the uncontrollable rage meaning comes later, followed by the colloquial sense of angry.

It seems to be a common pattern, that a technical phrase for a mental condition gets borrowed for colloquial use and then falls out of usage in its original sense to avoid offense. Retarded is another example: the use of the word as an insult and synonym for unintelligent put it onto the Euphemism treadmill.