A loan (noun) is a sum of money that will be repaid, or permission to use something for a period of time.
“I have applied for a loan. I want to go back to school.”
The phrase “on loan” is an idiomatic expression.
The exhibit is on loan from the museum.
The verb loan is accepted in American English as a substitute for lend:
Can you loan me some money until my next paycheck?
Do not substitute loan for figurative uses of lend, such as:
Can I lend a hand?
Lend me your ears.
The verb lend can be used in several ways:
We are not in a position to lend you money at this time.
The complexity of the subject does not lend itself to summary description.
Recent evidence lends credence to the theory.
Note: The past tense (and past participle) of lend is lent.
“Charles lent me his car while mine was in the shop.”
“I wish to thank my editor, who has lent considerable support and expertise to this project from the outset.”
loan or borrow?
When you wish to borrow something, you seek a loan, and you become the borrower:
Can I borrow your copy?
I borrowed the money for the operation.
When you allow someone to borrow something from you, (i.e., you lend it), you are the lender:
“I lent you money last month.”
Borrowed and loaned are not interchangeable!
I borrowed money from the bank. ✓
The bank loaned me money to buy a car. ✓
My sister borrowed me her coat. X
(My sister lent me her coat. Or: My sister loaned me her coat. ✓)