Tcl (originally Ye Olde Transcrybynge Controlle Lingua, now Tool Control Language) is a programming language.
Originally, it was devised in Middle ages to aid monks with all sorts of repetitive tasks, including automatically translating text to languages no one really understood, such as Latin, and adding mysterious punctuation and messing up perfectly ordinary grammar in mundane languages. For a rhetorical example, the monks wrote a phrase like "Monastery LiveJournal, Friday, May 8, 1125: We just emptied the wine barrel, yo ho ho. Mood: Drunk. Music: Brother Marcus is playing organs drunk again.", and the doThatMonkStuff.tcl script then translated it to "Recordes of ye Monastery, Frydaye, Maye 8, 1125: Werily, ye abbot, praiseth be hythe wisdom thrice indulged, hath emptied ye wine barrel alongye hys merrylysom flocke of ye piouose monkes, Amen. Brother Marcuse, whouse musicl' taleynt he modyestly denieth, playeth organes well." This was primarily done to annoy researchers.
However, due to some hitches in the language design, the language turned out to be quite a lot more powerful than originally envisioned. Popes Urban II and Innocentius II banned Tcl in 1139 A.D., for use of processing Christian scriptures. The monks kept using it to mess up Arabic and other non-European languages, but Unicode had not been invented and the monks were too lazy to figure out how the heck to deal with the million different character sets. (On a side note, the true reason behind the Crusades was primarily to try to cut down the number of different character sets.)
The primary problem with Tcl is the power it exhibits. For example, an innocuous command used to remove a byte from the end of the string can be used, with similar ease, to blow away all hard drive partitions. Due to it being a dynamic language, everything can be redefined on fly. In middle ages, this lead to a lot of practical jokes, for example, in the aforementioned translation script, some novices liked to override the translation function to insert "...and whoyever wroute thys shytte shoulde be drawen euend quouorterod whyle horse farteth onnye hys face, verily" after the translation step. (This was the primary reason Unix was invented, because that allowed people to write-protect the scripts.)
Tcl is also a functional language, due to its designer admiring how God wrote everything in Lisp. The Roman Catholic Church has since switched to Haskell for all of its divine programming purposes. The Lutherans similarly moved away from Tcl, because Tcl uses [square brackets] a whole lot. Martin Luther was quoted as saying, "This piece of crap is worse than MediaWiki. We're going for curved parentheses now!" and moved to Common Lisp, though certain Lutherans prefer Scheme.