From The Collaborative International Dictionary of English v.0.48:
Letter \Let"ter\ (l[e^]t"t[~e]r), v. t. [imp. & p. p. Lettered (-t[~e]rd); p. pr. & vb. n. Lettering.] To impress with letters; to mark with letters or words; as, a book gilt and lettered. [1913 Webster] letter bomb
From The Collaborative International Dictionary of English v.0.48:
Lettered \Let"tered\ (l[e^]t"t[~e]rd), a. 1. Literate; educated; versed in literature. " Are you not lettered?" --Shak. [1913 Webster]
The unlettered barbarians willingly accepted the aid of the lettered clergy, still chiefly of Roman birth, to reduce to writing the institutes of their forefathers. --Milman. [1913 Webster]
2. Of or pertaining to learning or literature; learned. " A lettered education." --Collier. [1913 Webster]
3. Inscribed or stamped with letters. --Addison. [1913 Webster]