guidestone
nounEtymology From guide + stone.
1
A traditional stone marker providing directions for travellers.
- Arrived at Wellington's Monument, the way levels over Eaglestone Flat and passes a guidestone […] that is unusual in being inscribed on one face only: Chesterfeild Roade.1980, Arthur Edward Dodd, Evelyn Mary Dodd, Peakland Roads and Trackways, page 108:
2
Figuratively Something serving as a guide.
- Now, as a guidestone for modernization of the classical theory of meromorphic functions, a new revolution was born with discovery of two main theorems by R. Nevanlinna in 1925.1994, Mathematica Japonicae, volume 40, page 18: