One-word Substitution: Part 5

1. One who talks in sleep: somniloquent
2. One who makes scientific study of language: linguist
3. One who knows many languages: polyglot
4. One who enjoys another person's confidence: confidant
5. One who is appointed by parties to settle disputes: arbitrator
6. One who breaks in a house to steal: burglar
7. One who sails around stopping and robbing ships at sea: pirate
8. One who abstains from alcoholic drink: teetotaller
9. One who leaves his own country and goes to live in another: emigrant
10. One who comes to one country from another to settle: immigrant