scarlet letter(n = noun.communication) - the letter A in red; Puritans required adulterers to wear it;
is a kind of allegory, emblem

air letter, airmail letter, black letter, block letter, business letter, capital letter, chain letter, commercial letter of credit, cover letter, covering letter, crank letter, dead letter, encyclical letter, fan letter, form letter, investment letter, letter, letter a, letter b, letter bomb, letter bond, letter box, letter c, letter carrier, letter case, letter d, letter e, letter f, letter g, letter h, letter i, letter j, letter k, letter l, letter m, letter n, letter o, letter of credit, letter of intent, letter of jeremiah, letter of mark and reprisal, letter of marque, letter of the alphabet, letter opener, letter p, letter paper, letter q, letter r, letter s, letter security, letter stock, letter t, letter telegram, letter u, letter v, letter w, letter writer, letter x, letter y, letter z, love letter, lower-case letter, market letter, night letter, open letter, personal letter, polyphonic letter, runic letter, scarlet, scarlet bugler, scarlet bush, scarlet clematis, scarlet cup, scarlet fever, scarlet fritillary, scarlet hamelia, scarlet haw, scarlet lychnis, scarlet maple, scarlet musk flower, scarlet oak, scarlet pimpernel, scarlet plume, scarlet runner, scarlet runner bean, scarlet strawberry, scarlet sumac, scarlet tanager, scarlet wisteria tree, scarlet woman, sea letter, short letter, small letter, to the letter, traveler's letter of credit, traveller's letter of credit, upper-case letter, varsity letter