'bugbear' originates from Middle English, specifically the elements 'bugge' and 'bear', where 'bugge' meant 'a frightening thing or hobgoblin' and 'bear' referred to the animal (used to suggest a terrifying creature).

'bugbear' changed from the Middle English elements 'bugge' + 'bear' and was recorded in the 16th century as a term for a frightening creature; it later developed a figurative sense as a recurring object of dread or annoyance in modern English.

Initially, it meant 'a frightening goblin or monster', but over time it evolved into its current meaning of 'a source of persistent annoyance or fear (a pet peeve)'.