Definitions of falter:

• noun:   the act of pausing uncertainly
• verb:   be unsure or weak

  Example: "Their enthusiasm is faltering"

• verb:   move hesitatingly, as if about to give way
• verb:   walk unsteadily
• verb:   speak haltingly

  Example: "The speaker faltered when he saw his opponent enter the room"

• name:  A surname (very rare: popularity rank in the U.S.: #30450)