serious crime; grave offense
Refers to a crime of significant severity, often implying heavy punishment or moral weight.
彼は重い罪を犯してしまった。
He committed a serious crime.
重い罪には重い罰が科せられる。
A grave crime carries a heavy punishment.
Compound of 重い (heavy, serious) and 罪 (crime, sin). The phrase is transparent and follows standard adjective-noun modification.