Loan means credit when you loan to somebody giving that somebody credit. You are the loaner and the person given credit is the Lonee. Loaner is the lender and the Lonee is the borrower.
You can sue anyone. What you need to win the lawsuit though is evidence. You have to prove to the court that the other person you loaned money to did not pay it back and you also have proof that they...
Loans are not usually considered income for tax purposes.Added: UNLESS you, the lender, are earning interest on the loan. Then - the interest income is taxable.