Heuristic
A principle or aid, adapted to solving problems of some given type. Colloquially, a heuristic is a "rule of thumb".
In Go, many proverbs serve as heuristics. Heuristics should not be considered hard and fast rules, just as we are advised "Don't follow proverbs blindly".
heuristic (1): adjective: serving to guide, discover, or reveal; specifically: valuable for empirical research but unproved or incapable of proof. (German heuristisch, from New Latin heuristicus, from Greek heuriskein to discover; akin to Old Irish fuar and Greek eureka! I have found)
heuristic (2): noun 1: the study or practice of heuristic procedure; 2: heuristic argument
The common usage in computing, especially artificial intelligence, is as a noun meaning a technique to be tried by a program when a direct definitive algorithm or exact solution is not available.