Literally 'in sillicon' - though not actually that obviously, 'in computer'. A slightly tongue in cheek phrase for modelling natural systems using programs 'n stuff. Computational chemistry, molecular modelling, bioinformatics, and so on are all at the boundary of traditional in vitro science and the new silaceous disciplines.

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In silico is aptly derived without a doubt as a computer scientist’s pun after the late 19th century biological and biochemical terms in vivo and in vitro. In vivo describing experiments conducted “in the living body of a plant or animal’ and in vitro indicating research that takes place “outside the living body and in an artificial environment” such as a petri dish or test tube for example. Put these two ideas together and the evolution becomes the modern Latinism in silico as research done with biological data stored on silicon chips.

It’s a funny phrase that smacks of a Latin derivative, but is the buzzword good Latin? Well it depends on which Latinist you ask. One expert uses a reference that goes back to the ancient Roman poet T. Lucretius Carus citing a phrase from one of his books: totius subcava montis est natura fere silicum suffulta cavernis pointing out that: …… here silicum is genitive plural, either for "flint" or maybe for the opaline substance that stalagmites and stalactites are made of.
Almost all chemical elements have neuter form (even fluorine, chlorine, …would probably be fluroinum in Latin, hydrogen is Hydrogenium) so silicon, silici (like lexicon, i) would be good (L)atin for the element. Of course vitrum is made of SiO2 also and the semiconductor diodes, which make up transistors and integrated circuits are made of more than silicon. Maybe crystallum electroniferum would be "semiconductor."
Since the experiments are conducted in the computer and software rather than in the chips themselves, maybe the slangy English "in silico" would be more properly latinized as in computatro, in ordinatro Another linguist begins too with "flint" but reaches a less literal and eventually more practical conclusion to the etymology of the phrase:

    "Silicon" comes from Latin silex, silicis, meaning "flint."
    How to interpret the -on suffix? Is it a Greek-style consonant neuter stem in -on, like criterion. Criterion forms the plural criteria, and silicon relates in some way to silica... In this case, silicon is an imperfectly nativised Greek coinage, and the correct case ending would indeed be in silicoin Latin.

    Or is the -on suffix related, as Random House relates it, to the endings of boron and carbon. Carbon represents Latin carbo, carbonis, (meaning) "charcoal." This has the minor merit of being native Latin; but it changes the declension to a masculine consonant stem. If we go this route then the correct form would be in silicone. This written form would suggest a false etymology and an incorrect pronunciation in English. If people are actually out there saying in silico, perhaps that should settle it.

The earliest citation in print to date is in the July 21 issue of Newsday magazine. Contributing writer Joshua Quittner talks about it in his 1992 article, Artificial Life Gets Real, "Some a-life researchers claim they are creating life forms on computers, in silico creatures as truly alive as the bacteria studied in vitro." A little over a decade later The Washington Post published an article on February 11, 2001 called “A New Genetic Window on Curing Diseases” by journalist Rick Weiss. From AI to genetics, here is how he uses the phrase “"Now, with the human genetic code at last published and loaded onto CD-ROMs and DVDs, scientists are talking about a new era of medicine in which medical discoveries will be made not 'in vivo' (in life) or 'in vitro' (in test tubes), but 'in silico,' or on computers."

In silico is possibly best known to the readers of the international journal on computational molecular biology In Silico Biology and in 2002 a book titled Everyone in Silico by Jim Monroe was published with mediocre reviews a Matrix-like scenario where San Francisco has been destroyed by an earthquake and replaced by the virtual city of Frisco where corporations monitor everyone, there is no privacy and it’s the physical that becomes the virtual reality. There are a number of scientific research papers that use the term in the text of their hypotheses. One award-winning scholar from Czechoslovakia remarks:

    After a careful docking and active site analysis, drug-like compounds from the ACD database were screened in-silico through the viral thymidine kinase and a new hit was found. I tested it in-vitro and the compound showed to be active. The trick was that I kept important water molecule in the docking site!
    (Pospisil, Pavel. The Role of Water in Drug Design: Thymidine Kinase as Case Study , 2002)
The “ACD database” is an acronym for the Available Chemicals Directory that allows scientists to search and display 3D models for over 200,000 molecular structures. A molecular modeling glossary defines in silico biology as: “Technological developments such as cDNA microarray-based RNA quantitation and proteomics have opened the opportunity for massively parallel biological data acquisition. This has shifted our attention towards a more complex understanding of molecular biology. In addition to determining the roles of individual genes, genetic network analysis enables us to study cells as a complex network of biochemical factors."

In recent and important example of the use of in silico technology was used to combat the efforts of terrorists who employ dark biology tactics. The in silico porject was initiated by the Department of Chemistry at the University of Oxford and the National Foundation for Cancer Research in 2002 called the Anthrax Research Project, a direct outcome of the incidences of the disease following the attacks on 11 September 2001. Sponsored by Intel, Microsoft, and United Devices, computer users from around the globe began a joint effort designed to help scientists develop a treatment for the Anthrax toxin. Idle computer time on over a million personal computers across the world were used to screen a database of billions molecules. The screening quickly facilitated the progression from the computational realm into the actual laboratory. In less than a month the computer based comparative analyses identified molecules as potential anthrax inhibitors dramatically reducing the time required for the drug discovery process with results shared with governments worldwide.

The evidence seems to indicate that what began as a psuedo-scientific term in the category of slang has found a place of distinction in the arenas of “dry discovery” techniques to experiment with biological replicas, drugs and health interventions using “sophisticated computer models rather than expensive laboratory and animal experiments.” Over the past decade the phrase has grown to include techniques in genomics and bioinformatics. The popular buzzword made it to the forefront in dictionaries for new phrases in 2002 and it seems like the term is here to stay. Today in silico is widespread in the specialized fields of the scientific press with many instances showing up scientific journals from articles entitled In Silico Fertilization Information Age Gives Birth to New Knowledge to job advertisements.

Sources:

Birgid Schlindwein's Hypermedia Glossary Of Genetic Terms:
hal.weihenstephan.de/genglos/asp/genreq.asp?nr=638

English Usage Archives:
www.yaelf.com/archives.shtml

in silico
:www.wordspy.com/words/insilico.asp

In-silico Screening for Anthrax Toxin Inhibitors:
www.chem.ox.ac.uk/anthrax/ -

LATIN In silico?:
omega.cohums.ohio-state.edu/hyper-lists/ latin-l/00-11-01/0010.html -

World Wide Words:
http://www.worldwidewords.org/weirdwords/ww-ins1.htm

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