Definition - What does Excusable Neglect mean?
Excusable neglect refers to the failure to take required action on time by any party or their lawyer for a court justified reason. This is practiced to prevent default judgment in case of failure to answer.
Justipedia explains Excusable Neglect
Common types of excuses the court may accept include illness, carelessness on the part of lawyer's staff, etc. Having said that, if the defendant fails to call their lawyer or loses the complaint then the court will likely to be less lenient.