tetragram

A tetragram is a four-letter sequence. The term derives from Greek tetra- "four" + gramma "letter" and is used in linguistics, cryptography, and textual analysis to denote any string of four letters that appears in sequence in a text.

In language processing, tetragrams are studied as four-letter units; they are a type of n-gram, with bigrams (two letters) and trigrams (three letters) common in frequency analysis, language modeling, and OCR. In some contexts, "tetragram" is used interchangeably with "quadgram" to refer to four-letter sequences, particularly in cryptography and statistical modeling.

The term also has a specialized sense in religious studies: the Tetragrammaton refers to the four-letter biblical name of God in Hebrew, YHWH. The precise pronunciation is not known; vocalizations such as Yahweh or Jehovah are scholarly reconstructions. Jewish and many Christian traditions treat the tetragram as sacred, often replacing it with "Adonai" or "Hashem" in reading or speech, while English Bible translations typically render it as "the LORD".

In modern scholarship, the tetragram is a neutral shorthand used to discuss the four-letter sequence or the four-letter name, depending on context.