IMO, it's the commonly used term whenever that particular door state needs to be described, (which, admittedly, might not happen that often). For me, it sounds much more natural than 'slightly open'. There may be a difference between British and American English here.

Both sentences are correct, but Sentence 2 is more natural in everyday conversation. Native speakers do use "ajar," but it's less common in casual speech. "Slightly open" sounds more natural and is easier to understand for most people. So, while "The door is ajar" is perfectly fine, "The door is slightly open" is what you'd hear more often in daily conversations. You're doing great! Keep learning! 😊

Hi Phonenew. That word "ajar" is mainly seen in car notifications and maybe some manuals / texts. In every day conversation (in this context) "open" is more widely used

"Ajar" is definitely a word that you can use. Perhaps it might not be used a lot, but that is not a reason to avoid it. English has zillions of words, some used frequently, and others less so. Rather than avoid infrequently used words, I suggest that you incorporate more of them into your active vocabulary. Here's a good question to type into Artificial Intelligence: "Please give me a list of words in English, like 'ajar', that are actively, but infrequently, used in English."

Us as native speakers do not use the word Ajar in everyday conversation . The 2nd option is something you would hear us say when we speak.