The phrasal verb "sit down" is primarily used in informal contexts, although it can also be used in formal contexts when giving polite instructions. Typically, it is used to describe the act of taking a seat or advising someone to be seated. For instance, hosts may ask guests to "sit down" to commence a meal or during meetings when a discussion is about to begin. While "sit down" itself denotes a simple action, it can also be metaphoric in contexts where it involves engaging in a discussion or addressing a serious matter (e.g., "We need to sit down and talk about your performance"). It is a versatile phrase appearing in everyday conversations, often softened with politeness elements, such as "please" or "would you." The phrase can appear as a command, an offer, or a polite suggestion, making it a common and flexible component of both spoken and written English.
A2
Elementary
1. To move from a standing position to a sitting position.
I decided to sit down after walking all day.
She asked him to sit down before giving the speech.
2. To meet with others to discuss something in an organized way.
Let's sit down and talk about your concerns.
We should sit down with the team to plan the event.