A more thorough explanation:

A dilatory defense is a type of defense used in a lawsuit that temporarily obstructs or delays the case but does not address the merits. Examples of dilatory defenses include misjoinder, nonjoinder, res judicata, misnomer, lack of capacity to sue, another action pending, statute of limitations, prematurity, unripeness, release, and settlement.

For instance, if a defendant in a lawsuit claims that the plaintiff filed the lawsuit too late, the defendant is using a dilatory defense. This defense does not address the substance of the case but rather seeks to delay the proceedings.