Does this phrase was observable use correct grammar?

The phrase "this phrase was observable" is grammatically correct, but it's likely not the most natural way to express the idea.

Here's why:

* "Observable" typically refers to something that can be seen or noticed. A phrase itself isn't something that can be directly observed.

* The phrase implies that the speaker is referring to a specific phrase that was previously mentioned or understood. It would make more sense to provide context for what phrase you're referring to.

Here are some examples of how you might rephrase the sentence depending on your intended meaning:

* If you're saying the phrase was noticeable or noteworthy: "This phrase was striking." or "This phrase was memorable."

* If you're saying the phrase was actually present: "This phrase appeared in the text." or "This phrase was used in the discussion."

* If you're saying the phrase was something that could be studied: "This phrase was a subject of analysis." or "This phrase was examined for its meaning."

Let me know if you can provide more context about the phrase you're referring to, and I can give you a more accurate and natural way to express your idea.