Complex sentence: The order Nidovirales is named for the Latin nidus, meaning nest, referring to this order's production of a 3' co-terminal nested set of subgenomic mRNA's during infection.
Split into simpler sentences: The order Nidovirales is named for the Latin nidus, which means nest. It refers to this order's production of a 3' co-terminal nested set of subgenomic mRNA's during infection.