This idiom describes being completely controlled, dominated, or influenced by someone else, as if held firmly under their thumb like a small object. It conveys a state of subjugation or powerlessness, often used in personal, workplace, or social contexts to depict an imbalance of power. The phrase carries a tone of oppression, resignation, or critique, reflecting cultural values of autonomy and the human tendency to exploit or submit to authority. Its physical imagery evokes a sense of being trapped or diminished, resonating in scenarios like overbearing relationships or authoritarian leadership. The idiom highlights the dynamics of control and resistance, making it a striking metaphor for situations of dominance and compliance.

The phrase originated in 18th-century Britain, likely tied to physical gestures of authority, where pressing a thumb symbolized control, as in wrestling or discipline. Its earliest recorded use appears in Samuel Johnson’s *A Dictionary of the English Language* (1755), noting ‘under the thumb’ as a colloquial term for subjection. The idiom gained traction in 19th-century literature, particularly in Charles Dickens’ *Great Expectations* (1861), where characters are described as under domineering influence. Its spread was amplified in the 20th century through political and social commentary, notably in British newspapers discussing labor or gender dynamics. Its adoption across English-speaking cultures, especially in the U.K., U.S., and Australia, stems from its vivid imagery and universal applicability to power imbalances, from domestic life to corporate hierarchies.