(Stephanus pagination) 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.

plural of letter opener

plural of letter grade

A letter written in superscript, usually when it indicates an abbreviation.

The customary certificate of national character which neutral merchant vessels are bound to carry in time of war; a passport for a vessel and cargo.

plural of letter box

In Ancient Rome, one of the first eight letters of the alphabet, which were repeated successively from the first to the last day of the year. One of these always expressed the market day, which returned every nine days (every eight days by our reckoning).

(now rare) A corporal with responsibility for carrying or delivering letters for a given regiment etc.

plural of letter corporal

(printing) Two letters on one shank; a ligature. / An item of mail requiring double postage.