noun
shrine name post; stone pillar with shrine name
A stone pillar or post placed outside a Shinto shrine, typically inscribed with the shrine's official name. Often found at the entrance or along the approach.
神社の入り口に社号標が立っている。
A shrine name post stands at the entrance of the shrine.
この社号標には「八幡宮」と刻まれている。
This stone pillar is inscribed with 'Hachimangu'.
石碑 is a general stone monument, whereas 社号標 specifically marks a shrine's name.
Compound of 社号 (shrine name) + 標 (marker, sign). The exact historical origin is uncertain, but the term is used for stone pillars bearing a shrine's official name.