A balloon payment mortgage is a mortgage which does not fully amortize over the term of the loan, thus leaving a balance due at maturity.
Loan assumption is the ability of a new borrower to take over a loan -on the same terms- from the original borrower.
A "teaser rate" or "start rate" are terms used to describe the ARM introductory rate for the initial fixed interest period.
Loan Margin is the difference between the mortgage loan rate and its underlying index (on which the note rate is based).
ARMs have a specific length of time between interest rate adjustments. In times of falling interest rates, a shorter period benefits the borrower.