Abandonment of trademark or tradename

What does Abandonment of trademark or tradename mean in American Law?

The definition of Abandonment of trademark or tradename in the law of the United States, as defined by the lexicographer Arthur Leff in his legal dictionary is:

Merely allowing the mark or name to “lie fallow” will not work an abandonment; enough more must be shown to permit the inference of intent permanently to give up the mark or name.