The 1944 Bletchley Park Cryptographic Dictionary

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AITKENISMUS :

(in Enigma) A type of near-cilli, arising from the tendency to avoid repeated letters in outside indicators; the occurrence of this may (with luck) be detected by assuming a cilli and calculating back to the possible message-settings that follow from this assumption; if one of these agrees in two letters with a recognizable type (e.g, keyboard, pronounceable, etc.) but not in the third letter, and if the adjustment which the third letter requires would produce a final position having a repeated letter, the presence of 'Aitkenismus' is indicated.

ALPHABET :

1. The letters and/or other signs or symbols employed in a particular code or cipher.

2. The order in which the letters and/or other signs or symbols employed in a particular cipher are arranged to represent the plain language letters (and other signs, if any) in their natural order for a particular key-letter or number. This order is often "hatted" and the "hatting" may be different for each different key-letter or the ssme alphabet may be "slid" cyclically according to the key-letter; (in Enigma) the thirteen substitution letter-pairings at any given position of the wheels. See also cipher alphabet.

3. (in Enigma key-breaking when the ringstellung is known or assumed) The complete series of possible stecker for a group of letters in a chain.

ALPHABETIC, ALPHABETICAL :

1. (of letters). occurring or arranged in their usual or natural order.

2. Employing letters or groups of letters

3. (spec. of code-books). Having the code-groups so assigned to the various items of the vocabulary that when the latter are arranged in alphabetical order the former are also in their natural order i.e. in numerical order in the case of figure-groups and alphabetical order in the case of letter-groups), and so permitting both encoding and decoding to be performed with one series of equivalents; unhatted; one-part, cf. Hatted. Two-part.

AMIR :

(in Enigma) A Crib sent from B.P. to Washington to be run on the naval bombes there.

ANAGRAM. n :

Plain language reconstructed from a transposition cipher by restoring the letters of the cipher text to their original order.

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