Middle English nouns. nification of the ways of expressing plural number.

In ME, when the Southern traits were replaced by Cen¬tral and Northern traits in the dialect of London, this pattern of noun declensions prevailed in literary English. The declension of nouns in the age of Chaucer, in its main features, was the same as in Mod E. The simplification of noun morphology was on the whole completed. Most nouns distinguished two forms: the basic form (with the "zero" ending) and the form in -(e)s. The nouns original¬ly descending from other types of declensions for the most part had joined this major type, which had developed from Masc. a-stems The process of eliminating survival plural forms went on in the 15th and 16th centuries. Forms like eyen, fon, which were still used by Chaucer, were now superseded by the regular forms eyes, foes. In several substantives with final [f] or [0] alteration of the voiceless fricative with its voiced counterpart was eliminated. This is the case with roof (plural roofs) and other words in -oof; also with belief (beliefs), death (deaths), hearth (hearths). However, with other substantives the alternation has been pre¬served, as in wife (wives), life (lives), half (halves), calf (calves), wolf (wolves); bath (baths), path (paths), youth (youths). With a few words two variants are possible: scarf (scarves, scarfs), truth (truths -6z, -0s). The substantive staff (OE staef, pl. stafas, ME staf, pl. staves) split into two separate words: staff, pl. staffs, and stave, pl. staves. The alternation [f — v] begins to extend to the word handkerchief, whose second part is of French origin; alongside the plural form handkerchiefs a new form handkerchieves is occasionally used. A few substantives have preserved their plural forms due to the weak declension or to mutation: ox (oxen), child (children), man (men), woman (women), foot (feet), goose (geese), tooth (teeth), mouse (mice), louse (lice), dormouse (dormice); here also belong the forms brethren (alongside brothers) and kine (alongside cows). Another type of plural has been preserved in the forms of the words sheep (sheep), deer (deer), swine (swine); compare fruit (fruit), also fish (fish), and names of several kinds of fish: trout, salmon, cod, etc., which usually take no -s in the plural. This peculiarity appears to be due to the meaning of these words. Most of them are names of animals (ox, goose, mouse, louse, dor¬mouse, sheep, deer, trout, salmon). The plural of these nouns is used to denote a mass (a flock of sheep, a herd of swine, a shoal of fish, etc.), rather than a multitude of individuals. This semantic pecu¬liarity appears to have influenced the plural forms of these words. As to the other words belonging here (man, woman, tooth, etc.) there must have been some other causes which determined their peculiar fate. Isolated plural forms have also been preserved in a few phrases which coalesced into compound words: twelvemonth (ОE twelf monap, fortnight (OE feowertyne niht), sennight (obsolete) (OE seofon niht).