The 1944 Bletchley Park Cryptographic Dictionary

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FOSS SHEET :

A sheet of squared paper (having 26 small squares along each side distinguished by the letters of the alphabet in their natural order) designed for recording occurrences of bigrams or larger groups, or letters, bigrams, etc. associated with other bigrams.

FOSS SHEET v :

To enter or record on a Foss sheet.

FRACTIONATING :

(especially). Bifid or trifid.

FREEBORN, a :

Performed, produced, or obtained by means of the (hollerith) electrical calculating, sorting, collating, reproducing, and tabulating machines in Mr. Freeborn's department.

FREEBORN, v :

To list, arrange, analyse, or otherwise deal with cipher material by means of (Hollerith) electrical machines to aid cryptographic investigation.

FREEBORNERY :

1. Mr. Freeborn's department; Block C.

2. Any form of register, difference-book, stencil-search table, or other aid to cryptographic investigation produced in Mr. Freeborn's department.

3. The processes or operations involved in producing the above.

FREQUENCY COUNT :

1. A record of the frequency of occurrence of single letters (or figures), bigrams, or other groups, especially code-groups, in a given quantity of material.

2. A similar record of the frequency of occurrence of single letters, bigrams, trigrams, etc. in suitable plain texts (e.g. those provided by deciphers) of a particular language, usually arranged both alphabetically and according to the frequency, as an aid to cryptographic research.

FREQUENCY DISTRIBUTION :

Diagram or record showing relative frequencies, especially of individual letters of the alphabet in a representative text of a particular language, or of the individual letters or other symbols of a particular cipher.

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