Development of the English Vocabulary from the 12th to 19

The “one-to-one” replacements
It has been calculated that from 80 to 85% of the OE words went out of use in the succeeding periods. Most of these words were not simply lost; they were replaced by other words of the same or similar meanings. The replacement came as a result of the co-existence and rivalry of synonyms and the ultimate selection of one of the rivals. Thus OE clipian came to be replaced by ME callen, NE call; OE niman was ousted by ME taken, NE take; the pronouns hie and heo were substituted for by they and she; OE weorðan was replaced by become; NE river took the place of OE ēa; NE table — the place of OE bord and so on and so forth.
Replacements could also occur in the sphere of content: the word was retained but its meaning was changed or was replaced by a new meaning. Thus OE drēam meant ‘joy’ but acquired an entirely different meaning, formerly rendered by OE swefn; OE cniht ‘boy, servant’ changed its meaning to ME and NE knight; OE clerec ‘clergyman’ developed into ME clerk ‘student, scholar’ and NE ‘secretary in an office’. Sometimes the meanings of the word changed when its referent (the thing it denoted) underwent some kind of changes, for instance, ME carre ‘wheeled vehicle’ now indicates a motor car or part of a train (sleeping car), NE car, Early ME carriage; coche denoted an old form of carriage pulled by four horses, while its descendant, NE coach, has acquired the meaning of ‘car, carriage’ in a train.

2. 
   Additions
   

The “one-to-one” replacements illustrated by the examples above did not increase the number of words in the vocabulary. Most replacements however belonged to the “split”-type: one item was replaced by two or more, or one meaning differentiated into several meanings. These changes should be classified as additions to the vocabulary.
Additions embrace a large number of vocabulary changes. The sum total of this type of change far offsets the process of obsolescence and decay. Among additions we can find pure innovations, that is entirely new words which did not take the place of any other items but were created to name new things, new ideas and new qualities, e.g. ME cite ‘town with a cathedral’, duke, duchesse, prynce — new ranks and titles; NE bourgeois, potato, nylon.
Many additions to the vocabulary were due to the differentiation of synonyms. The co-existence of synonyms did not necessarily result in the ousting of one by the other. Both words — or even several words of close meaning — could survive with certain differences in stylistic connotations, combinability and other features. For instance OE neah, near, neara survived as ME neer, its ME synonyms were cloos and adjacent, their NE descendants and synonyms: near, close, adjacent, neighbouring. Another example: OE heard, ME hard, ferme, solide, NE hard, firm, solid, severe.
The development of new meanings in the existing words extended the vocabulary and led to the growth of polysemy and homonymy. For instance, OE cræft meant ‘science’, ‘skill’, ‘strength’; in ME and NE craft lost the meaning ‘science’ but acquired new meanings ‘group of skilled workers, guild’ and ‘vessel’; ME journee meant ‘day’s work’, sometimes ‘day’s march’, later ‘travel, journey’.