A term describing certain of the offal or edible internal organs of beasts (not, of course, birds). This includes the heart, liver and kidneys. The tongue is also said to belong in this category.
"Giblets in the style of Burgundy" meaning giblets cooked in red wine with herbs, diced bacon, onions, mushrooms and livers.
Giblets cooked in white wine with herbs, chestnuts, grilled chipolatas, onions, mushrooms and pork belly.
Some people erroneously refer to this as meaning offal: the edible internal organs, such as kidneys, liver, heart, feet, etc of beasts (not, of course, birds). This is more properly referred to as 'abats'. Abattis or abatis (an arcane spelling) actuallys refers to giblets of fowl and feathered game.
Abattis de gibier à plume is a somewhat tortologous expression. These are the cheaper edible internal organs, including the gizzard, a muscular organ which acts as second stomach, heart and neck. Abatis do not include the liver, crest and kidneys, which are used in haute cuisine. Abatis alone means the giblets of a bird, but this does define it as being of game birds rather than domesticated poultry.