Origins
The word 'science' has undergone one of the most significant semantic narrowings in the history of Eβββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββnglish, transforming from a general term for any kind of knowledge into the specific designation for empirical, systematic investigation of the natural world. Its etymology reveals that the very concept of knowledge was originally understood as an act of separation or discernment.
The word enters English in the fourteenth century from Old French 'science,' itself from Latin 'scientia,' meaning 'knowledge,' 'skill,' or 'expertise.' The Latin noun derives from the present participle 'sciΔns' (knowing) of the verb 'scΔ«re' (to know). The further origin of 'scΔ«re' is traced to the PIE root *skey-, meaning 'to cut,' 'to split,' or 'to separate.' The conceptual leap from 'cutting' to 'knowing' is illuminating: to know something was to discern it, to separate it from what it is not, to make distinctions. Knowledge, in this ancient metaphor, is the blade that cuts through confusion.
The same PIE root *skey- produced a rich family of words in Latin and English. Latin 'scindere' (to cut, to tear) gave English 'scissors,' 'rescind' (to cut back), and 'abscissa' (a line cut off). Greek 'skhΓzein' (to split) produced 'schism' (a splitting apart) and 'schizophrenia' (a splitting of the mind). The conceptual thread of 'cutting apart to understand' runs through the entire family.
Scientific Usage
In English, 'science' initially meant any body of knowledge: theology, grammar, and music were all 'sciences' in medieval usage. The 'Seven Liberal Arts' of medieval education were routinely called 'the seven sciences.' This broad sense persisted well into the eighteenth century β Samuel Johnson's Dictionary (1755) defined science simply as 'knowledge' or 'certainty grounded on demonstration.'
The narrowing to 'empirical study of nature' occurred gradually during the seventeenth and eighteenth centuries, driven by the Scientific Revolution and the institutional separation of natural philosophy from other forms of learning. Francis Bacon, Robert Boyle, and Isaac Newton all called themselves 'natural philosophers,' not 'scientists.' The word 'scientist' was not coined until 1833, when William Whewell β a Cambridge polymath β proposed it at a meeting of the British Association for the Advancement of Science. Whewell modelled 'scientist' on 'artist,' arguing that just as an 'artist' practices 'art,' a 'scientist' should practice 'science.' The term was initially controversial; many practitioners considered it vulgar and preferred the older 'man of science' or 'natural philosopher.' Michael Faraday reportedly refused to be called a scientist.
The compound 'conscience' (from Latin 'con-' + 'scientia') literally means 'knowing together with oneself' β an internal witness to one's own actions. 'Conscious' and 'consciousness' derive from the same construction. 'Omniscient' (all-knowing), 'prescient' (fore-knowing), and 'nescient' (not-knowing) all preserve the Latin root in transparent form.
Proto-Indo-European Roots
German took an entirely different path: 'Wissenschaft' (science) comes from 'wissen' (to know), from a different PIE root (*weyd-, to see). Where the Latin tradition conceived knowledge as cutting, the Germanic tradition conceived it as seeing β two ancient metaphors for the same human activity, each preserved in a modern word.