Origins
The English verb 'amuse' has undergone one of the more dramatic semantic reversals in the language's history, transforming from a word implying deception and stupefaction into one of lighthearted entertainment. The journey from 'to stupefy' to 'to delight' took roughly two centuries and tells us something about how English speakers gradually softened a word's edges through habitual use.
The word enters English in the 1480s from Old French 'amuser,' which meant 'to cause to muse,' 'to distract,' or 'to cause to stare stupidly.' The French verb is composed of 'a-' (to, toward — ultimately from Latin 'ad-') and 'muser,' a verb meaning 'to stare,' 'to ponder idly,' or 'to loiter.' The etymology of 'muser' itself is contested. One theory connects it to Medieval Latin 'musum' (snout, muzzle), suggesting the image of an animal standing with its nose in the air, gaping vacantly. Another theory traces it to a Gallo-Romance root related to idleness or dawdling.
In its earliest English use, 'amuse' had nothing to do with entertainment. It meant 'to divert the attention of,' often with implications of deception. Military writers used it to describe diversionary tactics: a general might 'amuse' the enemy with a feint while launching the real attack elsewhere. Diplomatic contexts were similar — one might 'amuse' a rival with false negotiations while preparing an ambush. The word carried a distinct flavor of trickery.
Development
A secondary early meaning was 'to put into a muse' or 'to stupefy' — to leave someone staring blankly, absorbed in puzzled thought. This sense appears in seventeenth-century texts where someone is 'amused' not because they are laughing but because they are bewildered or distracted.
The transition to the modern meaning — entertaining, causing laughter or pleasant diversion — happened gradually during the seventeenth and eighteenth centuries. The logical chain is traceable: to divert attention leads to to occupy attention pleasantly, which leads to to entertain. By the time Samuel Johnson published his Dictionary (1755), 'amuse' had acquired its modern sense, though Johnson still included the older meanings.
The related word 'bemuse,' formed with the intensifying prefix 'be-,' has retained more of the original bewildered sense. To be 'bemused' is to be puzzled or confused, not entertained — though this distinction is frequently blurred in modern usage, much to the frustration of prescriptive grammarians.
Later History
The noun 'amusement' followed the same semantic arc. An 'amusement' was originally a distraction or a means of passing time; by the nineteenth century it had become firmly associated with entertainment. 'Amusement parks,' first so called in the 1890s, embedded the word permanently in the vocabulary of leisure and pleasure.
The verb 'muse' — to think deeply or meditatively — is generally considered the same word as Old French 'muser,' though its modern English sense has been heavily influenced by association with the Muses, the Greek goddesses of arts and inspiration. This is technically a case of folk etymology: 'muse' (to ponder) and 'Muse' (the goddess) have different origins, but centuries of association have blurred the boundary in most speakers' minds. The word 'museum' genuinely derives from the Greek 'mouseion' (seat of the Muses) and is not related to French 'muser.'
French 'amuser' has maintained a broader range than its English descendant, covering both 'to entertain' and 'to waste time' — 'arrête de t'amuser' can mean 'stop fooling around' as much as 'stop having fun.' This wider French usage preserves something of the word's original connection to idle distraction that English has largely lost.