useless trivia: What Word Means: Making Pig Sounds?

Questions

Old World bird with plain brown plumage, inhabiting marshes and similar habitats?

A brook or stream, rivulet?

Rounded green ish citrus fruit with an acid fleshy pulp?

Artificial satellite used as a base for scientific and medical research?

Policy of acceding to the demands of a potentially hostile country in the hope of maintaining peace?