Unselfish.
The antonym for alcoholic with the prefix "non-" added is "nonalcoholic."
The antonym for "perfect" by adding a prefix is "imperfect." The prefix "im-" indicates negation, transforming the meaning to suggest something that is not perfect or has flaws. This term is often used to describe things that fall short of an ideal standard.
discomfort
Tidy
dont know
One possible prefix for "selfish" is "un-", which would create the word "unselfish," meaning not selfish.
The prefix is -in, as in "incapable."
beside unselfish
Selfish.
Greedy.
prefix
The prefix "ir-" before "regular" would create the antonym "irregular."