Question

what is the name for rbc’s that are sticking together like a “stack of coins”?

Explanation:

In the field of medicine and health (a subfield of Natural Science), when red blood cells (RBCs) stick together in a stack - like - coins appearance, this phenomenon is called agglutination or rouleaux formation. Rouleaux formation specifically refers to the stacking of RBCs like a stack of coins, often due to factors like increased plasma proteins.

Answer:

Rouleaux (or Agglutination, but Rouleaux is more specific for the stack - of - coins appearance of RBCs)