The phrase "tucks one tail" is a colloquial expression used to describe someone who is scared, timid or submissive. There are a number of synonyms that can be used to convey this meaning, including "cowardly," "timorous," "fearful," "apprehensive," "fainthearted," "timid," "anxious," "nervous," "startled," "terrified," and "shy." Each of these words conveys the notion of being afraid or intimidated, and can be used in a variety of contexts to describe someone who is feeling vulnerable or uneasy. Whether in literature, conversation, or everyday life, these synonyms for "tucks one tail" offer a rich and nuanced vocabulary for describing human emotions and behavior.