Two of the more interesting suffixes borrowed by English and put to good neologistic use are -naut and -nik. The origins of the word ‘naut’ have connotations of travel and water, Naut derives from an Ancient Greek word, translated as ‘naútēs‘, meaning ‘sailor’, sometimes rendered as ‘to navigate’. From naut we get the word ‘nautical’, something nautical relate of course to water and ships, although the root word naut has been employed to form new words which relates more to the sky or to atmosphere rather than to water.
✒︎ The Argonauts
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The first use of this suffix in the above sense seems to emanate from Greek mythology and the story of Jason and his crew who sailed according to legend in search of the Golden Fleece – the Argonauts. The etymology is: Classical Latin Argonauta; from Classical Greek Argonautēs; from Argō, Jason’s ship + nautēs, sailor; from naus, ship [Webster’s New World College Dictionary]. The Shorter Oxford English Dictionary on Historical Principles dates it’s use in English from 1596, so it’s been in currency for a long time.
The post-war phenomenon that has given naut words their impetus and continued relevance was the Space Race from the late 1950s, initially involving only the USSR and the United States. The US space program brought astronaut into common use , a word formed by simply conjoining the prefix astro (= stars) with naut. Far from being newly coined, the word itself has a history that long pre-dates the 1950s and 60s “Race to the Moon”. In 1930 the term was used in a pioneering Sci-Fi short story, ‘The Death’s Head Meteor’ by Neil R Jones (and there are other instances of the word in fiction go back to the late 19th century). The explorations of space fired the popular imagination, propelling astronaut into common usage to describe those (especially American) who ventured into space on behalf of the “Free World”. Astronaut may have been influenced by the term aeronaut (aero meaning air or atmosphere, as in aeronautics, from Ancient Greek aēr = air) in use to describe balloonists dating from the 1780s [http://en.m.wikipedia.org/wiki/Astronaut]. With the long-term goal of reaching the Moon accomplished by the US in 1969 and further Moon missions planned, it was of no surprise that the more precise lunarnaut soon crept into the vocabulary.
As the Soviet Union entered the bipartite race with the intention of ‘conquering’ space and establishing a technological superiority over the US, the Russian Cold Warriors wanted for ideological reasons naturally enough to differentiate their extra-planetary achievements from those of their capitalist foes. So when the first successful spaceman Yuri Gagarin went up in Vostok I in 1961, the word cosmonaut (from Cosmos, the Universe, from Ancient Greek Kosmos = order) came into the lexicon – the New York Times attributed its genesis to Premier Khrushchev “and Soviet publications” [‘Russians coin a word for him: “Cosmonaut”, NYT, 13 April 1961].
✒︎ “astroboy” touches down
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The expansion of the Space Race to other nations outside of the big two spawned a whole lot of other naut-based neologisms. The first Indian in space (1984) was initially depicted as a cosmonaut (because he flew under the Soviet space program), but Indian pride and patriotism and the advancement of their own, homegrown space program, soon led to the evolution of a distinctive term for Indian space-traveller, vyomanaut (from Sanskrit vyoman (= sky). Although among Hindi-speakers there has been some debate about the rival merits of other terms, eg, there is a measure of support for anthanaut (or antharnaut), derived from anthariksh, meaning ‘space’ in Hindi.
When China joined the “Man-in-Space Club” by launching their own pilot beyond the stratosphere in 2003, the Chinese inevitably found their own term to describe it – tàikōnaut (taikon the Chinese word for space or cosmos, derived from tàikōngrén = spaceman) [‘Taikonaut’, Language Log, http://languagelog.ldc.upenn.edu/]. Although it was apparently a Chinese-Malaysian who first used the term for Chinese astronaut and the Xinhua News Agency uses it in its English-language publications (but not the Shenzhou space program).
NB: For a pure Chinese rendering of the concept, either hángtiānyuán or yūhángyuán (literally translated as sky navigator or sailor and Universe navigator or sailor respectively) more accurately capture the essence of the meaning [ibid.]
Another word invented to describe the profession of space explorer of a specific country or region is spationaut, meaning a French astronaut, from Fr: spationaute (= space navigator). Spationaut is also used more generally to delineate astronauts from other European states, although a more suitable, generic term for this might be Euronaut.
Along the lines of aeronaut we also have aquanaut which might be a grander way of describing an underwater diver (the prefix ‘Aqua’, from Ancient Greek for water), which is distinct from an oceanaut whose scientific marine exploration is done in a submarine. 
✒︎ A NASA aquanaut (source: theatlantic.com)
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Other -naut-suffixed terms signifying navigation in either a precise or looser sense include:
• chrononaut (a time-traveller – inspired by Doctor Who or Back to the Future?)
• cryonaut (one whose body is preserved by cryonics)
• cybernaut (a voyager in cyberspace; user of the internet or virtual reality. Could also be called an infonaut)
• gastronaut (person with a keen appreciation of food, ie, a more formal name for a ‘foodie’)
• hallucinaut (a hallucinator)
• neuronaut (one who studies the brain especially the effects of psychedelic drugs). cf. psychonaut who explores one’s own psyche under the effects of drugs.
• oneironaut (one who explores dream worlds)
As can be gleaned from the above there is a high degree of artificiality in the construction of many of these naut words. Some involve the choice of a convenient word (eg, gastronaut) rather than involving an act of literal navigation. Another concocted naut word with an interesting medical-related origin is responaut. The term was first applied c.1964 to a group of people at a particular facility in England with severe breathing difficulties whose condition needed them to be attached virtually permanently to the newly invented iron lung (mechanical respirator) in order to preserve their lives. ‘Responaut’ (formed from combining respirator + naut) was chosen because these patients experience similar problems to astronauts and oceanauts in establishing and maintaining communications and vital air supplies [Sunday Times (Lon), 12 January 1964, cited in Word Finder (Oxford English Dictionary), http://findwords.info/term/responaut].
The word Juggernaut contains the form of the naut suffix only by coincidence. It it unconnected to the idea of navigation or sailing, having come into English currency from a difference language group. Juggernaut derives from Sanskrit via a Hindi word, jagannath, meaning literally, world lord or protector. In English it has come to signify anything to which persons blindly devote themselves to or are ruthlessly crushed by [Shorter OED on Historical Principles].
Yinglish and spacerace-speak
Turning to words with the suffix ‘nik’, these come to English from a different path being of Slavonic origin with some Yiddish influence. Nik suffixes are very common in Slavonic languages, we find for example polkovnik (meaning colonel) in Russian, Polish, Czech, Bulgarian, Ukrainian and so on. Just as the Space Race gave naut words a new impetus, nik also found its way into English from Russian after the Soviet Union’s successfully launched a space craft named Sputnik in 1957.
The word beatnik was coined by journalist Herb Caen [San Francisco Chronicle, 2 April 1958] to describe adherents to the “Beat Generation”, a sort of subculture movement characterised by youthful anti-conformism, rebelling against the mainstream and hip culture (“being cool, man!”) (cf. the word ‘hipster’ as used today). Other traits include devotion to jazz, drug use and Eastern religions, and pseudo-intellectualism. Through the writings of ‘Beat’ leaders such as Jack Kerouac, other neologisms followed the pattern of beatnik … jazznik, bopnik, bugnik [Jack Kerouac, Brandeis Forum, ‘Is there a Beat Generation?’, 8 Nov. 1958, www.wnyc.org/story/.]
The Cold War tensions of the 1970s spawned another new word formed from the root nik – refusenik. Originally, refuseniks were individual citizens (many Jewish but not exclusively so) of the USSR and other Eastern Bloc countries who were denied permission by the Communist authorities to emigrate. Over time the application of ‘Refusenik’ in colloquial English has broadened to take on the meaning of “a person who refuses to do something, especially by way of protest” [Oxford English Dictionary (online)].
Peacenik is a word which has often been used in a derogatory way to describe someone who is an activist or demonstrator who opposes war and military intervention [www.dictionary.reference.com/browse/peacenik] (cf. “woke”/”wokeism”).The term is thought to have originated in the 1960s [possibly 1962 according to www.wordorigins.org]. Its precise origin is not known but very likely the term arose out either out of the anti-nuclear weapons movement or the anti-Vietnam War movement of the sixties. Peacenik is a synonym for pacifist or dove.
Holics – taking it to the nth degree
An unrelated but similarly manufactured word to peacenik is peaceoholic (sometimes spelt peaceaholic). Peaceaholic and other words with an -aholic or -oholic postfix are back-formed by analogy with the word alcoholic (into English from Arabic via French or Middle Latin). So we have shopaholic, workaholic, chocoholic, sexoholic, etc. which convey the sense of an addiction to or obsession with an activity or object.
Other nik words with a Yiddish flavour to them include Nudnik and Kibbutznik. Nudnik means obtuse, boring, a bothersome person a pest (nudyen = to bore). The Jewish Chronicle reports (18 February 2009) that Nudnik has entered modern Hebrew … “a common and even respected modus operandi in Israeli society”. A nudnik is someone “who is constantly asking you for something or otherwise taking up your time” [www.thejc.com]. Kibbutznik is a name given to workers who are members of an Israeli collective farm (a Kibbutz).