gravamen (n.) Look up gravamen at Dictionary.com
1640s, "grievance," from Late Latin gravamen "trouble, physical inconvenience" (in Medieval Latin, "a grievance"), literally "a burden," from Latin gravare "to burden, make heavy, weigh down; oppress," from gravis "heavy" (from PIE root *gwere- (1) "heavy"). Specifically, in law, "part of the accusation which weighs most heavily against the accused." Related: Gravaminous.