root

root

A root is often seen as part of word; it can never stand by itself though it bears clear, definite meaning; it must be combined with another root or an affix to form a word, e. g. liter-in literal, and literature.
(P51)：词根经常被看成是单词的一部分,尽管它具有比较清晰、确切的意思,却不能够独立存在,它必须和其他词根或词缀一起才能构成一个单词。这样的词根在英语里数不胜数。