Lethie is of French origin, derived from the ancient French word 'lethe', which means 'moon'. It was originally a place name, referring to a location named after the moon. Over time, it evolved into a given name and is now quite rare, adding an air of uniqueness to those who bear it.
The name Lethie had three peaks in popularity during the late 19th and early 20th centuries, with five babies named Lethie born each in 1896 and 1918, and eight in 1926. Altogether, there were eighteen individuals named Lethie over these years.