be short of, not have, be deficient in, need, require
Short, shy.
deficiency
be without
Lack, want,
lack dearth
lethargic
incommunicado
Inaction??
Another word for "lack of interest" is apathy or indifference. These both basically refer to a person who is uninterested, unresponsive or impassive. Another word to describe this sort of person could also be perfunctory.
Lazyness
lacking skill
Harsh truth
to lack to deprive to sacrifice
benighted; lack of knowledge, uncultivated; etc;