lubricant UK /ˈluːbɹɪkənt/US /ˈlubɹəkənt/noun 2forms 1phrases 1 noun2 •A substance used to reduce friction between objects or surfaces.Before you apply the lubricant, be sure the chain gets a good cleaning with a stiff bristle brush and a good rub down in clean rags or shop towels. — 2008 •A personal lubricant. formslubricants Phrases with lubricant social lubricantA food, beverage, drug or activity that helps people feel more comfortable in social occasions.