Reprehensible means deserving of blame or strong criticism. It is a strong word — your mother might forgive you for doing something bad, but something reprehensible? That's worse.
If a politician steals funds that are meant to provide care for the elderly, that's reprehensible! Near synonyms of this adjective are "blameworthy" and "culpable." The word reprehensible is from Middle English, from Latin reprehensus, plus the suffix -ibilis, "deserving of, capable of." If someone is reprehended, they are blamed or strongly criticized.