Ah, another trick question. Hollandaise is the French word for the adjective Dutch. In theory, the word refers to anything related to the Netherlands and its citizens, but in the food world, it refers primarily to sauce hollandaise, or Hollandaise sauce, a classic mixture of eggs and butter.

Hollandaise sauce is the mother sauce in the family of warm egg-emulsified sauces (as opposed to cold egg-emulsified sauces, such as mayonnaise). Hollandaise sauce is the basis for a number of variations that include capers, orange juice, tangerine juice, key lime juice, horseradish, mustard, anchovies, and whipped cream.

Madeleine Kamman, author of The New Making of a Chef (Canada, UK) - a book you really must have if you are going to be a cook, says Hollandaise sauce is also the basis of béarnaise sauce. Your cooking school instructors may disagree, but that is a lesson for another day.