Ectotherms and cold-blooded animals are alternate names for poikilotherms.
These organisms are the thermoregulatory opposites of "endotherms" or "homeotherms," sometimes known as "warm-blooded animals," which can keep their body temperature reasonably high and consistent regardless of the temperature of their environment.
Stenotherms are animals that can only endure a relatively small range of temperatures.
Yes, poikilotherms primarily hibernate in the winter.