fish

The word 'fish' is one of the oldest continuously used nouns in the English language, traceable thro‌​‍​‌​‍​‍​‍​‍​‌​‌​‍​‍​‍​‍​‌​‌​‍​‍​‌​‌​‌​‌​‍​‌​‌​‍​‌​‍​‍​‍​‍​‌​‍ugh Old English 'fisc,' Proto-Germanic *fiskaz, and ultimately to Proto-Indo-European *pisk-, a root meaning simply 'fish.' It is a word that has changed remarkably little across five millennia of linguistic evolution, both in form and meaning.

The Old English form 'fisc' was pronounced roughly as modern English 'fish,' with the spelling 'sc' representing the /ʃ/ sound in late Old English. The word appears in the earliest surviving English texts, including Beowulf and the Anglo-Saxon Chronicle. In Old English, the plural was 'fiscas,' though the modern unchanged plural 'fish' (rather than 'fishes') developed in Middle English, possibly by analogy with 'sheep' and 'deer' — other animals that retain zero plurals, perhaps because they were thought of as collective masses rather than individual creatures.

The Proto-Germanic form *fiskaz is well attested across the family: Old Norse 'fiskr' (modern Icelandic 'fiskur,' Swedish and Danish 'fisk,' Norwegian 'fisk'), Old High German 'fisc' (modern German 'Fisch'), Old Saxon 'fisk,' Old Frisian 'fisk,' Dutch 'vis,' and Gothic 'fisks.' The consistency of the form across all Germanic branches confirms its antiquity.

The PIE root *pisk- produced Latin 'piscis' (fish), which in turn gave rise to a learned vocabulary in English: 'Pisces' (the zodiacal constellation and sign), 'piscine' (relating to fish), 'piscatorial' (relating to fishing), and 'piscivorous' (fish-eating). The initial consonant difference — 'f' in Germanic, 'p' in Latin — is one of the textbook examples of Grimm's Law, the systematic sound correspondence that Jacob Grimm identified in 1822 as defining the Germanic branch of Indo-European. PIE *p consistently became Proto-Germanic *f: thus *pisk- became *fiskaz (fish), *pəter became *fadēr (father), *ped- became *fōtuz (foot), and *pūr became *fōr (fire, compare Greek 'pyr').

The Irish word 'iasg' (fish) also descends from PIE *pisk-, though through a very different phonological pathway. The Celtic branch dropped the initial *p- (a characteristic Celtic sound change), producing Old Irish 'íasc' from earlier *piskos. This means that Irish 'iasg,' English 'fish,' and Latin 'piscis' are all reflexes of the same PIE word, disguised by millennia of independent sound change.

The semantic range of 'fish' has always been broader in everyday speech than in scientific taxonomy. In common English usage, 'fish' has historically included any aquatic creature: whales, dolphins, jellyfish, starfish, crayfish, and shellfish have all been called 'fish' at various points in history. The word 'whale' itself was sometimes glossed as a type of 'fisc' in Old English texts. The modern biological restriction of 'fish' to gill-bearing aquatic vertebrates is a product of Linnaean taxonomy (18th century), not of natural language development.

Compound words and derivatives built on 'fish' are extraordinarily numerous in English: 'fisherman,' 'fishhook,' 'fishpond,' 'fishwife,' 'fishmonger,' 'swordfish,' 'starfish,' 'jellyfish,' 'cuttlefish,' 'kingfisher,' 'fishing,' and many more. The verb 'to fish' (Old English 'fiscian') derives from the noun and has developed rich metaphorical senses: 'fishing for compliments,' 'a fishing expedition' (a legal investigation without specific evidence), and 'something fishy' (something suspicious — first attested in the early 19th century, perhaps from the idea that concealed fish produce an unmistakable smell).