since unknown year (earliest usage recorded on this site was 1982)
TI-BASIC is the unofficial name of a BASIC-like language built into Texas Instruments (TI)'s graphing calculators, including the TI-83 series, TI-84 Plus series, TI-89 series, TI-92 series (including Voyage 200), TI-73, and TI-Nspire. TI does not officially name the language, but only refers to it as "extensive programming capability". Though the TI-BASIC name has stuck, the syntax is different from almost all standard BASIC implementations, sometimes resembling other languages such as PILOT or even Forth.
NOTE: this is distinct from TI BASIC, which was used on the TI 99/4A home computer.