What is meant by base currency?
The base currency of a loan is the currency in which the payment schedule is calculated. If this is bitcoin, then borrower needs to repay the bitcoin loan amount plus interest. If US dollar is the base currency, the loan repayments are calculated in dollars. The actual payment is still conducted in bitcoin. But the amount of bitcoins that are repaid each month fluctuate with the bitcoin price. The value of the payment in dollars is fixed. This is done to mitigate bitcoin price fluctuations for borrowers and lenders.