Peanut oil (arachis oil) is an organic oil derived from peanuts, noted to have the slight aroma and taste of its parent legume. In the UK it is marketed as 'Groundnut Oil'.
Peanut oil was used as the original source of fuel for the diesel engine.
Peanut oil is most commonly used when frying foods, particularly french fries and chicken.
Commercial peanut oil will not cause an allergic reaction because the allergen is a protein, not a fat; however, the cold pressed and organic oils will. They are presumably less filtered, retaining some peanut proteins for the sake of flavor and nutrition.