What is meant by the technical terms:  domesticated, tame, feral

Domesticated

To train or adapt (an animal or a plant) to live in a human environment and be of use to human beings. Selecting (via natural or artificial breeding) animals with genes adapted to human needs.  These genetic changes are heritable.  For example, a boxer has selected those grey wolf's genes (from whom it is descended) that enable it to seize prey in its massive jaws and hold it until the hunters arrive to kill the animal.

Tameness

Behaviors in an animal that lead to a close relation to humans.  Taming is a conditioned behavioral modification of an individual, not a genetic change. 

A word about the difference between domestication and tameness:  Domestication is permanent genetic modification of a bred lineage that leads to, among other things, a heritable predisposition toward human association.  It's a heritable tameness.

'Taming' an animal can be done with obviously wild animals, like leopards and lions at the circus. Likewise, once an animal is domesticated a genetic change has been made to it and it cannot then ever be not-domesticated. It can live free of people however, in which case it's called feral.

Feral

1. a. Existing in a wild or untamed state. b. Having returned to an untamed state from domestication.

A ‘feral’ cat is a domestic cat that is living to a greater or lesser degree independently of direct human care. Feral cats are genetically domestic but have not been socialized. They may live in the ‘wild’, hunting natural prey, on the periphery of human activity, or as street cats in the center of our cities.

References

1. Letter from Carlos A. Driscoll of Oxford University to Scientific American readers
2. The American Heritage Talking Dictionary, Version 4.0, 1995.