tcsh

/tiːˈsiːˌʃɛl/

noun … “an enhanced version of csh with improved interactivity and scripting features.”

C Shell

/siːˈʃɛl/

noun … “a Unix shell with C-like syntax designed for interactive use and scripting.”

csh, short for C shell, is a Unix command-line interpreter developed by Bill Joy in the late 1970s. It introduced a syntax and command structure inspired by the C programming language, making it more familiar to programmers accustomed to C. csh enhanced interactive usability with features such as history substitution, aliases, job control, and built-in arithmetic, while also supporting scripting for automation of system tasks.

ksh

/keɪˈʃɛl/

noun … “a Unix shell that extends sh with advanced scripting and interactive features.”

sh

/ʃɛl/

noun … “the original Unix command interpreter for executing scripts and commands.”

zsh

/ziː ʃɛl/ or /zɛd ʃɛl/

n. "Extended UNIX shell blending Bourne compatibility with interactive superpowers like spelling correction and recursive globbing."