Acrostic is a stack-based programming language whose source code resembles a solved crossword puzzle. Acrostic code occupies a two-dimensional grid. Each instruction is a specific word in the grid, written either horizontally or vertically. Instructions typically have several synonyms, allowing the programmer to choose the word that fits best in their own crossword. Execution starts at a start word such as
prologue and runs until it hits the start word in reverse.