Origin of the "breach" sense of "compromise"

Both wiktionary and etymonline give the origin of compromise as Latin com (together) + promittere (promise). This is the most common use of this word: to mutually promise to [abide by an arbitrated decision.]

However, the word also has the sense of impairing or breaching, as in "to compromise one's reputation [due to one's inappropriate action]" or "to compromise national security [by revealing information]." Where did this meaning of compromise originate?

Solution 1:

Since "compromise" developed from a Latin verb with a cognate in (almost?) all Romance languages (French 'compromettre', Spanish 'comprometer', Portuguese 'comprometer', Italian 'compromettere', Romanian 'compromis'), it may be useful to look it up in etimological dictionaries in other languages. In this case, I found an Italian etimological dictionary (etimo.it) that relates 'compromettere' as "agree" and as "put in danger". Here's a rough translation:

Compromèttere: from Latin COM-PROMITTERE. To put in arbitration some decision, each part agreeing to obbey whatever is to be decided. Since this way to put an end to controversies could expose oneself to danger because of a decision that could turn out to be unfair but unappealable, the word Compromettere ended up being used to say "to put (something or someone) in danger with actions not meditated upon".

The shift in meaning from "arbitrate" to "expose to danger" is present in most Romance languages (I can tell it is in Spanish, Italian and Portuguese). M-W defines "compromise" as:

• to expose (something) to risk or danger
• to damage or weaken (something)

I cannot assert the process of shifting from one meaning to another in English was the same as it was in Italian, but it could be useful as an insight. The thing is, such process is registered in at least one language, so maybe it's a good thing to start with.

Solution 2:

It came from a sense it developed in English that it doesn't have in Latin. In English, this coming together to reach a promise or agreement became synonymous with the part of the process in which one concedes some of what they initially set out to get. Compromise then became married to the idea of concession, of giving up ground, of somewhat losing in original position.

When someone is compromised in the sense that you describe, it means that they have lost ground, they've been breached, they've lost their position, and so they are no longer viable. They in essence become like a compromise lost at the negotiation table: off the table.