J

JITTER
Short-term variation in data packets that usually results from varying time delays in transmission due to different paths or routing processes used in a packet communications network.

K

KB
KiloBytes - 1,024 bytes 

KBPS
Kilobits per second

KERBEROS
Software technology that guards computer systems against unauthorized intrusions by requiring third party authentication of an attempted access. Described in RFC 1510, KERBEROS is a mechanism involving the granting of tickets that permit servers to authenticate clients requesting use of their services.

KERMIT
From Kermit after the Muppet show
Kermit software offers a consistent approach to file transfer, terminal emulation, script programming, and character-set conversion on hundreds of different hardware and operating-system platforms, using diverse communication methods. Kermit is a file transfer protocol first developed at Columbia University in New York City in 1981 for the specific purpose of transferring text and binary files without errors between diverse types of computers over potentially hostile communication links, and it is a suite of communications software programs from the Kermit Project at Columbia University. Over the years, the Kermit Project has grown into a worldwide cooperative nonprofit software development effort, headquartered at and coordinated from Columbia University. The Kermit protocol was named after Kermit the Frog, star of the television series, The Muppet Show, used by permission of Henson Associates, Inc.