Teaser Rate

What Does Teaser Rate Mean?
An initial rate on an adjustable-rate mortgage (ARM). This rate will typically be below the going market rate, and is used by lenders to entice borrowers to choose ARMs over traditional mortgages. The teaser rate will be in effect for only a few months, at which point the rate will gradually climb until it reaches the full indexed rate, which will be a static margin rate plus the floating rate index to which the mortgage is tied (usually the LIBOR index).

Investopedia explains Teaser Rate
The use of teaser rates tends to grow dramatically during times when long-term interest rates move toward historical lows. Lenders stand to make much more money on ARMs if interest rates rise, while borrowers with ARMs will be faced with high interest payments.