The story
Stephanus (the surname of the writer of a famous early translation (in 1578) of the dialogues of the Ancient Greek philosopher Plato) + letter
Etymology from Wiktionary, CC BY-SA 4.0.
Stephanus letter
Today it means: A standard reference letter (either a, b, c, d, or e) for a one-fifth–equal-part subdivision of a given section (denoted by the preceding Stephanus number) of a given Platonic dialogue. Full definition →