Free Morphemes自由语素:可以独立成词的语素 eg:popular,teach
Bound Morphemes 黏着语素 不能独立成词的语素 eg:ise,er
When a word is formed,there is always a morpheme that serves as the root,which is the base of the word.eg:the root of enable is able,(free root 自由词根) the root of astronomy is astro(bound root 粘着词根)
Stem 词干 formed by a root and an extra bound morpheme,which can be either an independent word,or a base to which an extra bound morpheme can be added.Such as : root-construct stem--construction stem---constructional
Affix词缀
circumfix 环缀:环缀既有前缀又有后缀的特征-前后加缀的特征