SIGPLAN NOT refers to the Special Interest Group on Programming Languages' Negation operation. When it comes to synonyms for this term, various alternatives can be used interchangeably to convey the same meaning. Some common options include "opposite", "inverse", "contrary", "reversed" or "negated". These words help express the idea of negation or negating something. Whether in programming or everyday language, these synonyms can be employed to enhance clarity and precision in communication. Utilizing synonyms enables individuals to diversify their language usage and convey the same information in alternative ways, fostering effective communication and understanding.