Jumpy is a word that helps describe someone who is easily startled or nervous. There are many synonyms for this word that could be used to give meaning to the same, including skittish, jittery, twitchy, nervous, restless, uneasy, apprehensive, agitated and edgy. Each of these synonyms represents the behavior of someone who is prone to sudden movements or reactions due to fear or anxiety. Skittish is a word often used to describe horses that are quick to startle and move abruptly, while jittery is more commonly used to describe human behavior. All in all, these synonyms provide a clear picture of someone who is feeling anxious or scared.