C / O or “care of” means that the mail is for someone who is not the legal occupant of the address. Learn how to use C / O in mailing addresses effectively and accurately with examples and tips. Definition: In English, c/o stands for “ care of .” It is used on envelopes, address forms, and ID proof (like an Aadhar card) to show that something is sent via a person or address different from the actual recipient. Co or & Co. in company names means “Company” or “and Company.” Understanding what does C/O mean in mailing is essential for sending mail accurately. Whether for business correspondence, temporary stays, or third-party handling, using C/O correctly ensures mail reaches the intended recipient. C / O or 'care of' means you're sending correspondence to someone via another party. Learn when and how to use it, and see examples of its use in different situations.