A large portion of the technical and scientific lexicon of English and other Western European languages consists of classical compounds. These are compound words composed from Latin or Ancient Greek root words.
Not all Western European languages have been equally receptive to classical technical compounds. German, for instance, has historically attempted to create its own technical vocabulary from native elements. Usually, these creations are German calques on the international vocabulary, such as Wasserstoff for hydrogen. Like any exercise in language prescription, this endeavour has been only partially successful, so while official German may still speak of a Fernsprecher, public telephones will be labelled with the internationally recognized Telefon.
Thus, for example, Ancient Greek σφιγξ becomes English (and Latin) sphinx. Exceptions to these romanizing rules occur, such as leukemia (leukaemia); compare leukocyte, also leucocyte. In Latin, and in the target languages, the Greek vowels are given their classical values rather than their contemporary values in demotic Greek.
Ancient Greek words often contain consonant clusters which are foreign to the phonology of contemporary English and other languages that incorporate these words into their lexicon: diphthong; pneumatology, phthisis. The traditional response in English is to treat the unfamiliar cluster as containing one or more silent letters and suppress their pronunciation, more modern speakers tend to try and pronounce the unusual cluster. This adds to the irregularities of English spelling; moreover, since many of these words are encountered in writing more often than they are heard spoken, it introduces uncertainty as to how to pronounce them when encountered.
Classical compounds frequently vary their stressed syllable when suffixes are added: ágriculture, agricúltural. This also gives rise to uncertainty when these words are encountered in print. Once a classical compound has been created and borrowed, it typically becomes the foundation of a whole series of related words: e.g. astrology, astrological, astrologer/astrologist, astrologism.
Not all English writers have been friendly to the reception of classical vocabulary. The Tudor period writer Sir John Cheke wrote:
and therefore rejected what he called "inkhorn terms".
Similar sentiments moved the nineteenth century author William Barnes to create "pure English," in which he sought to strip out all Ancient Greek and Latinisms and find Anglo-Saxon equivalents therefor: for Barnes, the newly invented art of the photograph became a sun-print. Unlike this one, some of Barnes's coinages caught on, such as foreword, Barnes's replacement for the preface of a book. Later, Poul Anderson wrote a jocular piece called Uncleftish Beholding in a constructed language based on English which others have called Ander-Saxon; this attempted to create a pure English vocabulary for nuclear physics.
In the metric system, prefixes that indicate multipliers are typically Greek in origin, such as kilogram, while those that indicate divisors are Latin, as in millimeter: the base roots resemble Greek words, but in truth are neologisms. These metric and other suffixes are added to native English roots as well, resulting in creations such as gigabyte. Words of mixed Latin and Greek lineage, or words that combine elements of the classical languages with English, were formerly castigated as "barbarisms" by prescriptionist usage commentators; this disapproval has mostly abated. Indeed, in scientific nomenclature, even more exotic hybrids have appeared, such as for example the dinosaur Yangchuanosaurus. Personal names appear in some scientific names such as Fuchsia.
Classical compounds are sometimes used to lend grandeur or the impression of scientific rigour to humble pursuits: the study of cosmetology will not help anyone become an astronaut. Compounds along these models are also sometimes coined for humorous effect, such as odontopodology, the science of putting your foot into your mouth. These humorous coinages sometimes take on a life of their own, such as garbology, the study of garbage.
Some classical compounds form classical plurals, and are therefore irregular in English. Others do not, while some vacillate between classical and regular plurals.