허깨비

Meaning

1. 1.

   phantom; illusion; ghost — An object that looks like another or seems to exist although it is not real, due to an illusion stemming from mental or physical weakness.

2. 2.

   being lightweight; being airy; being fluffy — A state of being much lighter than thought.

3. 3.

   weakling; wimp — (figurative) A person who is very weak physically or mentally even though he/she does not look like that outwardly.