Where does the term first 5-8 and second 5-8 come from in rugby?

Question

Where does the term first 5-8 and second 5-8 come from in rugby?

Answer 1

The terms first 5/8 and second 5/8 come from the world capital of Rugby, New Zealand.  The first 5/8 is the flyhalf, and the term implies a slightly deeper position than the halfback (scrumhalf).  The second 5/8 is the inside center.

Answer 2

New Zealand Rugby uses different terminology than other Unions.....

Their terminology describes exactly where a position stands on the field.....