FDX is an abbreviation that stands for Federal Express, which is a company that provides courier, delivery, and logistics services. Some common synonyms for FDX include FedEx, Express Mail, Parcel Post, USPS, and UPS. These companies are known for their fast and reliable delivery services, and they offer various shipping options, such as same-day delivery, overnight shipping, and standard ground shipping. Whether you're sending a document or a package, these courier services are a great way to ensure that your items are delivered on time and in good condition. So whether you choose FDX or one of its synonyms, you can rest assured that your shipment will arrive safely and promptly.