HST stands for Harmonized Sales Tax and is a term used in Canadian taxation. There are several synonyms for HST, including GST (Goods and Services Tax), PST (Provincial Sales Tax), and VAT (Value-Added Tax). These terms all refer to taxes imposed on products or services in Canada. While the HST applies to certain provinces that have agreed to use a harmonized tax, the GST and PST are charged separately in other provinces. The VAT is a similar tax system used in other countries around the world. Regardless of the specific terminology used, these taxes play an important role in supporting government programs and services.