Well, cavern...
The word "hole" is pronounced the same as "whole."
chasm
chasm
The word deepen means to cause to become more deep. For example, if you have a hole that is five feet deep and you dig it out so that it becomes six feet deep, you have deepened the hole.
Pit
A word that has the same meaning as another word is a synonym.
The word meaning "complete" is spelt whole. The word meaning "opening" is spelt hole.
The Greek word that chasm came from is the word abyss. An abyss is a very deep, deep hole that is so deep it never seems to have a bottom.
grudge
Deep Thinking
The word in the passage with the same meaning as instantly is "immediately."
"Gilgandra" is a Wiradjuri aboriginal word meaning "long water hole".