A straight line tattoo is a very simple and minimalistic design, and it can signify many different things. Some people may get a straight line tattoo to represent their journey in life, and that they have a straight path that they are staying true to. Others may use a straight line tattoo to represent their strength and resilience, as they continue to stay on the same path in life no matter what. In some cases, a straight line tattoo may signify eternity and an infinite journey in life. Ultimately, the meaning of a straight line tattoo is personal and can represent whatever the individual desires.