Vinculum is a noun that refers to a unifying bond.

The Latin word vincire (vin CHEER ay) means ‘bind.’ This word later evolved into our word of the day and is today frequently used in anatomy and math to refer to various kinds of chemical and mathematical bonds.

The word can also be used in a casual context. For example: After watching all those old westerns together, my father and I have formed a viculum that can never be broken. Now all we need is a few horses and posse and we’ll be joined at the hip forever.