Sit down Definition 1 of 4Pro Tip 1/3Standard Invitation Used when inviting someone to be seated. It's polite and commonly seen in social and professional settings. Welcome to our office, please sit down. Pro Tip 2/3Casual Direction Informally, it tells someone to relax or be at ease in a friendly environment. Come in and sit down, make yourself at home! Pro Tip 3/3In Transit Used in transportation to indicate that a traveler should take a seat after boarding. Please sit down quickly so the bus can depart.