Grease joint refers to a mechanical component that requires periodic lubrication, either to reduce friction or prevent the parts from rusting. However, there are several synonyms for the term that are used interchangeably. The most common term is the "lubrication point," which also implies the same meaning as a grease joint. Some other synonyms include "lubrication fitting," "lube point," "grease nipple," and "grease fitting." These terms are mostly used in the industrial or automotive industry but can also be used in daily usage. Overall, the synonyms for grease joint serve the same purpose and are crucial for the longevity and smooth operation of machinery.