An oil is a substance that is in a viscous liqui state ("oily") at ambient temperatures or slightly warmer, and is both hydrophobic, (immiscible with water, lit. water fearing) and lipophilic (miscible with other oils, literally "fat loving"). This general definition includes compound classes with otherwise unrelated chemical structures, properties, and uses, including vegetable oils, petrochemical oils, and volatile essential oils. Oil is a nonpolar substance.