godan verb (-ru), intransitive verb
get heavy; become heavier
Intransitive verb meaning that something becomes heavy in weight or feel. Modern everyday Japanese often uses 重くなる instead, so 重る can sound more limited or less colloquial.
雨を吸って、布が重った。
The cloth absorbed the rain and got heavy.
godan verb (-ru), intransitive verb
worsen; grow serious; become severe
Used of an illness, condition, or matter becoming more serious. For ordinary modern wording, 悪化する or 重くなる is often more common.
祖父は病が重り、しばらく入院した。
My grandfather's illness worsened, and he was hospitalized for a while.