Hypercorrection happens when people try to avoid making one type of ‘error’ in speech or writing, but overcompensate and apply the corrections to too many words. For example, those who habitually ‘drop’ their h’s sometimes add an h an just about any word beginning with a vowel when trying to speak ‘proper’.
One case of hypercorrection that has become part of the language is the saying ‘to eat humble pie‘, meaning ‘to behave or be forced to behave humbly; to be humiliated’. To word humble in this saying comes from the word numbles, which means the offal of a deer. In the 14th century, a numble pie was one made from such offal. By the 17th century, a pie of this type was called ‘an umble pie’, which eventually acquired an initial h through hypercorrection and became ‘a humble pie’.
Numbles comes from the Old French word nombles (loins), from the Latin lumbulus (little loin).
Other words the have changed in a similar way to numbles include apron – originally napron, newt – originally ewt. This kind of change of word boundries, which is common in English, is called metanalysis.