What is Etymology?
Etymology is study of the history of words. The development of a word is traced back as far as possible through ancient texts, and by comparative reconstruction, but often not to its absolute origin. The study is now subsumed under historical (diachronic) linguistics.
The word 'etymology', derived partly from Greek etumos, true, reflects the common misconception that older forms and meanings of words are superior to current ones. Early scholars produced many speculative false etymologies, for example, connecting Latin lucus, a wood, with lucere, to shine, on the superficial evidence that the words sounded alike and that the sun fails to shine in a wood. But since the 19th-century researches of linguistic scholars such as Grimm and the group known as the neogrammarians, etymology has been a more scientific study and words as dissimilar as beef and cow can now be reliably traced to the same reconstructed Indo-European word *g"ous, the former by way of the Latin bos, the latter through the Old English cu. However, there still remain disputed and dubious etymologies of words where evidence is scant. One such is big, which appears in Middle English with only an obscure proper name as a possible Old English antecedent.
Words can change their pronunciation (and spelling) in the way that Old English ham (sounding like modern harm) became modern home. These changes, often following general principles such as Grimm's Law, can be stated in terms of sounds, rather than individual words, and so are usually treated separately. The example just illustrated involves the Great Vowel Shift, which affected numerous English words according to their vowels, stress, and other features. Other examples are Old English ban becoming modern bone, stan becoming stone, and so on. Sweeping grammatical changes can also occur and these, too, are usually studied separately from etymology. For example, Old English nouns such as ham had a dative case, hams, now lost, as well as a genitive, hames, which became home's.
Etymology centrally concerns the many changes which affect only one, or a few, words in the same way at any given time. Examples are Middle English cheris losing its final s in becoming cherry, unlike most other words ending in s; the synthesis undergone by Old English dsegesege (literally, day's eye) in becoming daisy, no longer felt as containing more than one element; and the many gains and losses of words and senses of words. These idiosyncratic changes, though not understood well enough to be predicted, are often explained by such factors as the need for new words arising from new discoveries and concepts. These can be supplied by neologisms (germicide, hoover), loan words (ombudsman ), and by adding new senses to existing words (program in computing). Conversely, a word is lost as the need for its use is lost (for example, phagotum, an extinct musical instrument). Another factor is cultural association, such as that which accounts for Middle English bede, prayer, becoming bead (via the rosary).
Psychological factors also account for change, as seen for example in homonymic clash—the loss of one of two words that have come to sound the same where the meanings might lead to confusion (let, meaning 'hinder' being lost in the face of let, meaning 'allow'). Other psychological factors include analogical levelling, such as that which involved creating a new regular plural of book in place of the irregular Old English one (which should have given modern beech ), and interpreting cheris as a plural, creating a new singular by back-formation (cherry); and also popular, or folk, etymology—where speakers unconsciously re-interpret an obscurity to look more familiar (for example, pentice made into penthouse, bridegome changed to bridegroom); the shortening of redundantly long forms (seen in abbreviations like fridge and acronyms like radar); and the desire to be expressive (seen in the weakened hyperbole of starve which once meant exclusively 'die'). A third cause of change involves factors such as: imitation of prestige groups (whereby English needlessly borrowed air and uncle from Norman French, replacing Old English lyft and earn); nationalism (whereby German made a loan translation, or caique, of the international word telephone, from Greek 'far' and 'sound', to produce Femsprecher, rather than borrowing the foreign word).