Lubricant/ˈluːbrɪkənt/ Definition 1 of 2Pro Tip 1/3Technical Context Use 'lubricant' in mechanical or technical discussions where friction is a concern. Regularly check the lubricant levels in your machinery. Pro Tip 2/3Not Always Oil 'Lubricant' does not only refer to oil; it includes any substance that lubricates. Graphite powder acts as a lubricant for locks. Pro Tip 3/3Physical Properties A lubricant can be liquid, semi-liquid, or solid depending on its application. The door hinge needed a solid lubricant to stop squeaking.