Lock-and-key tattoos feature a lock and the key that opens it. Sometimes the key is attached to the lock with a ribbon or other material. Other times the lock is on one limb and the key is on the other.
According to SloDive, locks and keys symbolize protection, the safeguarding of that which is important. The exact meaning of a lock-and-key tattoo depends on the wearer, but the shape of the lock and proximity to its key can give some indication. For instance, a common lock-and-key tattoo features a heart-shaped lock. Naturally, such a tattoo relates to love, or "the key to one's heart." Sometimes the lock is tattooed on one person and the key on another, representing their relationship. A lock-and-key tattoo is also associated with marital fidelity.
Lock-and-key tattoos can also symbolize freedom. This is especially true of a lock drawn to represent a time when the wearer felt trapped, with the key integral to freeing that person.
Other options depend on phrases or pictures associated with the lock. For instance, if the wearer adds words such as strength or courage, the lock-and-key tattoo indicates those qualities are important to freeing what is inside. Alternatively, a lock can be hiding something mysterious, such as a shameful secret or evil thoughts.