Spot rate
The rate on an investment running from today to a single future date, with no payments in between.
How to read the number
These are the points of the zero-coupon curve; the valuation of any bond with several payments is assembled from them.
When the metric lies
The yield to maturity of a coupon bond is not a spot rate but a kind of average over the spot rates of all its payments. Substituting one for the other in a calculation does not work.
Also known as: zero rate, pure discount rate