Hextet

In computing, a hextet is a sixteen-bit aggregation, or four nibbles. As a nibble typically is notated in hexadecimal format, a hextet consists of 4 hexadecimal digits. A hextet is the unofficial name for each of the 8 blocks in an IPv6 address.
History.
Bob Bemer suggested the use of hextet for 16-bit groups in 2000. In 2011 an Internet Draft explored various alternatives for hextet such as "quibble", short for "quad nibble".
"Hextet" would more properly describe a 6-bit aggregation, whereas the exact term for 16 bits should be "hexadectet", directly related to the term octet (for 8 bits). However, because it is harder to pronounce, the short form "hextet" is used—in analogy to how "hex" is commonly used as an abbreviation for "hexadecimal" in computing. This usage of "hex" to mean 16 is also in line with the similar IEEE 1754 term "hexlet" indicating 16 octets.
Although the word "hextet" is not officially recognized in the IETF documents, the word is used in technical literature on IPv6 published after the Internet Draft. Official IETF documents simply refer to them as "pieces".
Cisco sources generally use the term "quartet" as does IPv6.com, a reference either to the four digit grouping or to the fact that it represents four nibbles; however, this term is also used by some to refer to a four-bit aggregation.