What term describes an intravascular clot that dislodges from its site of formation and travels with blood flow?

The question asks for the term that describes an intravascular clot that dislodges from its site of formation and travels with blood flow.

• A. Thrombus: A thrombus is a blood clot that forms and remains attached to the wall of a blood vessel. It does not travel.
• B. Aneurysm: An aneurysm is a localized, abnormal bulge or ballooning in the wall of a blood vessel. It is not a clot.
• C. Embolus: An embolus is a mass (such as a blood clot, air bubble, or fat globule) that forms in one part of the body, dislodges, and travels through the bloodstream to another part, where it can block a blood vessel.
• D. Haematoma: A haematoma is a localized collection of blood outside of blood vessels, usually in clotted form, often resulting from trauma. It is not a traveling clot within a vessel.

Based on the definitions, an intravascular clot that dislodges and travels with blood flow is an embolus.

The final answer is $\boxed{\text{C. embolus}}$