构词学（英国语言学分科学名，Morphology，组织与形态）是语言学的一个分支，研究单词(Word)的内部结构和其形成方式。如英语的dog、dogs和dog-catcher有相当的关系，英语用户能够利用他们的背景知识来判断此关系，对他们来说，dog和dogs的关系就如同cat和cats，dog和dog-catcher就如同dish和dishwasher。构词学正是研究这种单字间组成的关系，并试着整理出其组成的规则。

In linguistics, morphology /mɔːˈfɒlədʒi/ is the identification, analysis and description of the structure of a given language's morphemes and other linguistic units, such as root words, affixes, parts of speech, intonations and stresses, or implied context. In contrast, morphological typology is the classification of languages according to their use of morphemes, while lexicology is the study of those words forming a language's wordstock.