Grasiento vs. graso vs. grasoso
The Spanish words 'grasiento', 'graso', and 'grasoso' all translate to the English word 'greasy' or 'fatty' when referring to food, however, they are used in different contexts and may convey slightly different nuances.
Grasiento
'Grasiento' refers to something that is covered in or filled with grease or oil. Although it can be used to describe food, it is often linked with non-edible items too.
El motor del coche está muy grasiento.
(The car's engine is very greasy.)
El tocino está grasiento tras cocinarlo.
(The bacon is greasy after cooking it.)
Graso
'Graso' usually describes food that contains a high content of fat inherent to the product itself. This is typically in relation to the nature of particular foods.
La mantequilla es un alimento graso.
(Butter is a fatty food.)
Prefiero no comer alimentos grasos para mantener mi salud.
(I prefer not to eat fatty foods to maintain my health.)
Grasoso
'Grasoso' describes the texture or feeling of food - food that leaves a fatty or oily residue when touched or consumed. It does not necessarily refer to the inherent fat content of the food.
Este pollo está muy grasoso.
(This chicken is very greasy.)
No me gusta la sensación grasosa que deja el aceite de oliva.
(I don't like the greasy feel that olive oil leaves.)
Summary
While 'grasiento', 'graso', and 'grasoso' convey the idea of 'greasy' or ‘fatty’, their usage varies. 'Grasiento' often relates to surfaces coated with oil or grease, which can include but isn't limited to food. 'Graso' is more about describing foods that contain a high amount of inherent fat. Lastly, 'grasoso' focuses more on the fatty texture or sensation of certain foods.