liver (n.2) Look up liver at Dictionary.com
"one who lives (in a particular way)," late 14c., agent noun from live (v.).
liver (n.1) Look up liver at Dictionary.com
secreting organ of the body, Old English lifer, from Proto-Germanic *librn (source also of Old Norse lifr, Old Frisian livere, Middle Dutch levere, Dutch lever, Old High German lebara, German Leber "liver"), perhaps from PIE *leip- "to stick adhere; fat" (see leave (v.)).

Formerly believed to be the body's blood-producing organ; in medieval times it rivaled the heart as the supposed seat of love and passion. Hence lily-livered, a white (that is, bloodless) liver being supposed a sign of cowardice, Shakespeare's pigeon-livered, etc. Liver-spots, once thought to be caused by a dysfunction of the organ, is attested from 1730.