Forcemeat

Forcemeat is a mixture of ground, lean meat emulsified with fat. Emulsification can be achieved by grinding, sieving, or pureeing the ingredients. It can be smooth or coarse, depending on the desired consistency of the final product. Forcemeats are used in the production of numerous items found in charcuterie, such items include quenelles, sausages, pâtés, terrines, roulades, and galantines. Forcemeats are usually produced from raw proteins, except in the case of a gratin forcemeat. Proteins commonly used in the production of forcemeats include pork, fish (pike, weakfish, trout, or salmon), seafood, game meats (venison, boar, or rabbit), poultry, game birds, veal, and pork livers. Pork fatback is often used for the fat portion of a forcemeat as it has a somewhat neutral flavor.

There are four basic types of forcemeats, Straight, Country Style, Gratin, and Mousseline.

Straight forcemeats combine pork and pork fat and a dominant meat. Straight forcemeats use a Progressive grinding process.

Country-style forcemeats are much more course and are made from pork and pork fat, with some liver, and other garnish items.

Gratin forcemeats have some amount of the main meat sauteed and cooled before it is ground.
gratin means "browned"

and finally Mousseline which is a very light forcemeat. it is based in tender and lean white meats like shell fish, fish, veal and poultry.