Card Nicknames: The victory card, the sudden changes card, the triumph card, the force card, the conquest card, death.
Short meaning: This card could mean a quick victory or a clean break with the past. It's also the card that could represent a physical death. While the Ace of Swords is similar to the eight of cups (the "moving on" card), the Ace of Swords card usually signifies a sudden and complete change, for example someone deciding to just quit the job and move to another city.
Full meaning: In Lewis' book (see Sources), the one-word meaning of the Ace of Swords is "Death." The Ace of Swords often does represent a physical death.
Martello also attributed other negative meanings to the card -- "Often called the death card. Really a worried mind, doubt, delay, setback, bad news, the need to fight for one's rights, trouble, anxiety, expecting the worst. Interference in one's plans, being blocked, fearful anticipation. When this card touches the person being read, indicates one who is 'sick with worry,' depressed, sad." (Martello, p. 108)
However, the Ace of Swords can also represent a quick victory or victory by force. Sometimes it's called "the force card." Waite's divinatory meaning was "Triumph, the excessive degree in everything, conquest, triumph of force. It is a card of great force, in love as well as hatred. The crown may carry a much higher significance than comes usually within the sphere of fortune-telling." (Waite, Pictorial Key, p. 252)
Much like the Death card of the major aracana, the Ace of Swords can represent a transformation, but with the Ace of Swords the transformation is usually sudden and complete -- a clean break with the past. Peach described the card as "A new beginning, a rebirth. Victory, success, triumph, great force. A complete change of mind, including all aspects of the Querent's life." (Peach, p. 69)
Gettings said the card indicated "The beginning of some undertaking involving considerable effort and struggle." (Gettings, p. 126)