How many words are there in the English language? (来源：英语麦当劳www.EnglishCN.com)
There is no single sensible(明智的) answer to this question. It's impossible to count the number of words in a language, because it's so hard to decide what actually counts as a word. Is dog one word, or two (a noun(名词) meaning 'a kind of animal', and averb(动词的) meaning 'to follow persistently')? If we count it as two, then do we count inflections(语型变化) separately too (e.g. dogs = plural noun, dogs = present tense of the verb(动词)). Is dog-tired a word, or just two other words joined together? Is hot dog really two words, since it might also be written as hot-dog or even hotdog?
It's also difficult to decide what counts as 'English'. What about medical and scientific terms? Latin words used in law, French words used in cooking, German words used in academic(学术的) writing, Japanese words used in martial(军事的) arts? Do you count Scots dialect(方言)? Teenage(青少年的) slang(俚语)? Abbreviations(缩写)?
The Second Edition of the 20-volume Oxford English Dictionary contains full entries for 171,476 words in current use, and 47,156 obsolete(废弃的、过时的) words. To this may be added around 9,500 derivative words(派生词) included as subentries(分项). Over half of these words are nouns(名词), about a quarter adjectives(形容词), and about a seventh verbs; the rest is made up of exclamations(感叹),conjunctions(结合), prepositions(介词), suffixes(后缀), etc. And these figures don't take account of entries with senses for different word classes (such as noun and adjective).
This suggests that there are, at the very least, a quarter of a million distinct(明显的) English words, excluding(排除)inflections(语型变化), and words from technical and regional(地区的) vocabulary not covered by the OED, or words not yet added to the published dictionary, of which perhaps 20 per cent are no longer in current use. If distinct(明显的) senses were counted, the total would probably approach(接近) three quarters of a million.