-tion

The suffix '-tion' is one of the most common noun-forming suffixes in English and by far the most productive for Latinate verbs.‌​‌​‍​‌​‍​‌​‍​‌​‍​‌​‌​‍​‌​‍​‍​‌​‌​‌​‍​‌​‍​‌​‌​‌​‍​‌​‍​‌​‍​‌​‌​‍ It forms abstract nouns denoting an action, process, state, or result: 'action' (the doing of something), 'creation' (the making of something), 'solution' (the loosening / resolving of something), 'destruction,' 'information,' 'education.' It is ubiquitous in academic, technical, scientific, legal, and administrative English.

The suffix descends from Latin '-tiō' (genitive '-tiōnis,' accusative '-tiōnem'), a suffix that attached to the supine stem of a Latin verb to form an abstract noun. Latin 'actus' (done) plus '-tiō' gives 'actiō' (an acting, a deed — whence 'action'); Latin 'creātus' (created) plus '-tiō' gives 'creātiō' (a creating — whence 'creation'); Latin 'nātus' (born) plus '-tiō' gives 'nātiō' (a being born, a birth, a people — whence 'nation'). The '-tiō' suffix is itself a Proto-Indo-European compound of two deeper suffixes: *-ti- (a feminine abstract noun formant, as in Sanskrit 'gati,' going) and *-ōn (a nominalising suffix). This compound is stable across Italic and inherited into Latin from the earliest attested stages.

Because '-tiō' attached to the supine stem (which usually ends in -t-, giving '-ātiō,' '-ētiō,' '-ītiō'), English '-tion' words almost always show a '-t-' before the suffix: 'action,' 'nation,' 'creation,' 'oration,' 'duration,' 'intuition,' 'nutrition.' When the supine stem ended in '-d-' or '-s-' or involved a contraction, the '-t-' + '-tiō-' sequence resolved as '-sion' instead: 'decision' (from 'decīsus,' decided), 'fusion' (from 'fūsus,' poured), 'tension' (from 'tensus,' stretched), 'vision' (from 'vīsus,' seen), 'expansion' (from 'expansus,' spread out), 'invasion,' 'conclusion,' 'expression.' This is why modern English has parallel suffixes '-tion' and '-sion' — they are the same Latin suffix in different phonological environments.

The suffix entered English in the thirteenth and fourteenth centuries in a flood of Anglo-Norman and Latin vocabulary: 'action,' 'confession,' 'creation,' 'damnation,' 'description,' 'destruction,' 'determination,' 'direction,' 'education' (later), 'evolution,' 'generation,' 'information,' 'injunction,' 'inspection,' 'institution,' 'intention,' 'introduction,' 'invention,' 'legation,' 'meditation,' 'nation,' 'navigation,' 'notion,' 'observation,' 'opinion,' 'position,' 'prevention,' 'production,' 'profession,' 'protection,' 'question,' 'reaction,' 'redemption,' 'relation,' 'revolution,' 'salvation,' 'satisfaction,' 'solution,' 'temptation,' 'tradition,' 'tuition,' 'violation.' In Middle English these words could be spelled '-cion,' '-cioun,' or '-sioun,' reflecting French orthographic variation, and they were pronounced with /sjoun/ (see-OON) following French usage.

A characteristic sound change in late Middle English and Early Modern English turned /sj/ or /tj/ into /ʃ/ in this environment, giving the modern pronunciation /ʃən/ ('shun') for '-tion.' This is why 'nation' is pronounced 'NAY-shun' despite the 't' in the spelling. The same shift affected '-cian' (musician, politician) and '-sion' (mission, session). This is known as yod coalescence and was largely complete by the seventeenth century.

By the eighteenth century, '-tion' had become a productive English suffix capable of attaching to newly coined Latinate verbs: 'classification' (1814), 'organisation' (1700s), 'standardisation,' 'privatisation,' 'globalisation,' 'digitisation' (or -ization). The suffix '-ation' (from Latin '-atio,' the most common subtype of '-tio') is particularly productive, attaching to any '-ise' or '-ize' verb: 'realise > realisation,' 'modernise > modernisation,' 'stabilise > stabilisation.' This has made '-tion' the dominant noun-forming suffix in formal English, especially in administrative, scientific, and legal registers.

A consequence of this productivity is that '-tion' is heavily weighted in English bureaucratic and academic prose. Writers of plain English sometimes advise replacing '-tion' nouns with their verb equivalents ('take into consideration' > 'consider'; 'give consideration to' > 'consider'). This 'nominalisation' style is characteristic of formal English and can feel stilted when overused. Literary critics sometimes call it 'zombie nouns' — nouns that have eaten the verbs that gave them life.

Related suffixes in English include '-ion' (the broader category, of which '-tion' and '-sion' are specific forms), '-ation' (the most productive subtype, with specifically Latin '-ātiō' origin), '-ition' (from Latin '-ītiō,' as in 'addition,' 'edition,' 'nutrition,' 'partition,' 'tradition'), and '-tious' / '-tial' (adjective forms built on the same family, as in 'contentious,' 'partial'). A closely related noun suffix is '-ure' (from Latin '-ūra,' as in 'creature,' 'nature,' 'structure'), which is less productive in modern English.

The non-Latinate counterpart of '-tion' in English is the native Germanic '-ing' (forming gerunds / verbal nouns). 'Create / creation' parallels 'make / making'; 'decide / decision' parallels 'deciding.' The distinction is register: '-tion' for formal, academic, or abstract; '-ing' for everyday and concrete. Both are fully productive, and speakers choose between them based on context and tone.

Representative '-tion' nouns include: action, addiction, administration, adoption, adoration, ambition, application, association, assumption, attention, attraction, caution, celebration, classification, collection, combination, communication, competition, condition, conservation, consideration, constitution, construction, consumption, contribution, convention, conversation, cooperation, corporation, corruption, creation, decision (-sion), deduction, definition, demonstration, description, destruction, determination, direction, discussion (-sion), distribution, duration, education, elaboration, election, emotion, evaluation, evolution, exception, execution, exhibition, expectation, explanation, exploration, expression (-sion), extension (-sion), formation, foundation, function, generation, graduation, hesitation, identification, illustration, imagination, implementation, indication, information, innovation, inspection, instruction, integration, intention, interpretation, introduction, invention, investigation, legislation, limitation, location, meditation, motion, motivation, nation, navigation, negotiation, notation, notion, objection, obligation, observation, occupation, operation, opposition, organisation, orientation, participation, perception, petition, population, position, precision (-sion), preparation, presentation, prevention, production, profession (-sion), promotion, proportion, protection, provision (-sion), publication, punctuation, qualification, question, reaction, recognition, recommendation, reduction, reflection, regulation, relation, relaxation, religion, representation, reputation, resolution, restoration, revelation, revolution, satisfaction, selection, separation, session (-sion), situation, solution, station, suggestion, taxation, tension (-sion), tradition, transformation, transition, transportation, tuition, variation, version (-sion), vision (-sion).