Source : Webster's Revised Unabridged Dictionary (1913)

Cutthroat \Cut"throat`\ (k?t"thr?t`), n.
   One who cuts throats; a murderer; an assassin.

Cutthroat \Cut"throat`\, a.
   Murderous; cruel; barbarous.

Source : WordNet®

cutthroat
     adj 1: ruthless in competition; "cutthroat competition"; "bowelless
            readiness to take advantage" [syn: {fierce}, {bowelless}]
     2: capable of or conducive to bloodshed; "a cutthroat rogue";
        "a homicidal rage"; "murderous thugs" [syn: {homicidal}, {murderous}]
     n : someone who murders by cutting the victim's throat